Method of controlling a torque transmission system and torque transmission system for carrying out the method of controlling

ABSTRACT

A method of monitoring a torque transmission system with a manually switchable gearbox in the power train of a motor vehicle involves the utilization of at least one sensor unit at the input side of the torque transmission system to ascertain relevant positions of the shift lever of the gearbox and the driving torque of the engine of the motor vehicle. The thus obtained shift lever signals are memorized, together with comparison signals which are obtained as a result of filtering of the shift lever signals, and various characteristics of such signals are recognized and identified to indicate the intention of the operator of the vehicle regarding the switching of the gearbox. The thus obtained switching intention signals are transmitted to a controlled clutch operating system.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application is a divisional of U.S. patentapplication Ser. No. 09/563,094, filed on May 2, 2000, which is acontinuation of U.S. patent application Ser. No. 09/227,003, filed onJan. 7, 1999, which is a divisional of patent application Ser. No.08/788,011, filed Jan. 21, 1997, now U.S. Pat. No. 5,890,992 which is acontinuation of patent application Ser. No. 08/393,316, filed Feb. 22,1995, now U.S. Pat. No. 5,679,091, all of which are incorporated byreference in their entirety.

BACKGROUND OF THE INVENTION

[0002] The invention relates to a method of controlling a torquetransmission system, to a torque transmission system for carrying outthe method of controlling, and to a method of monitoring torquetransmission systems.

[0003] It is known from the vehicle industry that, when changing thetransmission ratio of a gear between a driving machine and a gearboxunit, the required clutching processes can be assisted or automated by acontrol or regulating algorithm. This facilitates the servicing of theengine unit or gearbox, and the clutching operation can be carried outin an energy saving manner with careful treatment of the materials.Furthermore, the control of a torque transmission system which ismounted at the output side of an automatic gearbox can be helpful, forexample, in undertaking or guaranteeing adjustment processes andprotective functions in the case of, for example, cone pulley beltcontact gearboxes.

[0004] WO 94/04852 discloses a method of controlling torque transmissionsystems in conjunction with an automatic gearbox. The torquetransmission system comprises a load branching out with a torqueconverter which is mounted in parallel with a friction clutch. Inaccordance with this method, a driving torque transmitted by an engineunit is broken up into a hydraulic part which is to be transmitted bythe converter and a mechanical part which is to be transmitted by thefriction clutch, such as a lockup clutch. A central computer unitdetermines or calculates, in dependency upon the relevant operatingcondition of the system, the torque which is to be transmitted each timeby the friction clutch. The remaining torque to be transmitted by thehydraulic torque converter constitutes the difference between theapplied torque and the torque transmitted by the friction clutch andcorresponds directly to a slip between the input and output parts of thetorque transmission system.

[0005] Such method of controlling can be resorted to only in conjunctionwith an automatic gearbox and a lockup clutch. However, theacceptability of automatic gearboxes is only minimal in many fields ofuse. Furthermore, a lockup clutch of such kind is cost-intensive andbulky.

OBJECTS OF THE INVENTION

[0006] An object of the invention is to provide a method of controllingwhich can be used practically universally, the regulating quality ofwhich is high, and which exhibits a clearly improved load changebehavior for torque transmission systems.

[0007] In addition, one should achieve cost advantages in comparisonwith conventional torque transmission systems. Furthermore, an object isto provide a torque transmission system which can be utilized for thepractice of such controlling method.

SUMMARY OF THE INVENTION

[0008] The above objects are accomplished in that the clutch torquewhich can be transmitted from an input side to an output side of atorque transmission system with or without load distribution orbranching out is utilized as a control value and such control value iscalculated and/or determined in dependency upon an input or drivingtorque.

[0009] This amounts to a realization of a torque matching concept. Thebasic concept underlying the method of such kind resides in controllingthe setting member primarily in such a way that the clutch torque whichcan be transmitted by the torque transmitting parts is mainly just aboveor just below the driving torque at the input side or drive side of thetorque transmission system.

[0010] As a rule, a torque transmission system must be designed for thetransmission of two to three times the maximum driving torque of adriving machine, such as an engine. However, the driving torque which istypical of the operation is but a fraction of the maximum drivingtorque. The torque matching renders it possible to establish only thatforce-locking engagement which is required between the torquetransmitting parts in lieu of a quasi permanent excessive overpressure.

[0011] A further advantage resides in the provision of a controllingmethod. In contrast to a regulation, the feedback of condition values ofthe torque transmission system is not absolutely necessary. It servesmerely for a possible enhancement of the control but is not required inorder to establish the operation of the torque transmission system. Thetask of a torque transmission system of such kind is to transmit torque.Therefore, it is expedient to use the transmittable clutch torque as acontrol value.

[0012] An advantageous embodiment of the invention is characterized inthat, in a method of controlling a torque transmission system with orwithout load distribution or branching out which controls the torqueadapted to be transmitted from an input side to an output side of thetorque transmission system, the latter comprises a sensor system fordetecting the values to be measured and a central control or computerunit which is connected with the sensor system, the torque which can betransmitted by the torque transmitting system being controlled in such away that the transmittable torque is calculated, adapted and controlledas a function of a driving torque, and deviations from an ideal stateare compensated for long-term through corrections.

[0013] Furthermore, it can be of advantage to resort to a method whichserves to control a torque transmission system, especially for motorvehicles, wherein the torque transmission system is installed in thepower flow downstream of a driving machine and in the power flowupstream or downstream of a shiftable device, such as a gearbox, andcontrols the torque which can be transmitted from an input side to anoutput side of the torque transmission system, and the powertransmission system includes a control or computer unit which is insignal connection with sensors and/or other electronic units, the torquewhich can be transmitted by the torque transmitting system beingcalculated as a function of a driving torque and being adaptivelycontrolled, with deviations from an ideal condition compensated forlong-term through corrections.

[0014] According to another embodiment, the control value can betriggered by means of a setting member supplied with a setting valuewhich is functionally dependent upon the transmittable clutch torque, insuch a way that the transmittable clutch torque lies within apredetermined tolerance range at a slip limit wherein this slip limit isreached when the effect of a torque being applied at the input sideexceeds the clutch torque which can be transmitted by the torquetransmitting parts.

[0015] The method according to such embodiment can be carried outparticularly in such a way that the torque which can be transmitted by atorque transmission system, such as a friction clutch and/or ahydrodynamic torque converter with or without converter lockup clutchand/or a starter clutch for automatic gearboxes and/or a turning setclutch and/or a torque transfer system connected in front of or behindan infinitely adjustable gearbox, such as a cone pulley belt contactgearbox, can be controlled as a function of a driving torque so that inthe case of systems with load distribution or load branching, such as ahydrodynamic torque converter with converter lockup clutch, the torquewhich can be transmitted by the clutch is determined in accordance withthe torque equation

M _(KSoll) =K _(ME) *M _(AN)

[0016] and

M _(Hydro)=(1−K _(ME))*M _(AN)

[0017] wherein the two equations apply for K_(ME)≦1 and

M _(KSoll) =K _(ME) *M _(AN)

[0018] and

M_(Hydro)=0

[0019] applies for K_(ME)>1 with

[0020] K_(ME) torque division factor

[0021] M_(KSoll)=desired clutch torque

[0022] M_(AN) applied torque

[0023] M_(Hydro)=torque transmittable by the hydrodynamic torqueconverter

[0024] and a torque difference between the torque M_(AN) applied to thetorque transmission system by the driving aggregate and the torqueM_(KSoll) transmittable by the clutch is transmitted through thehydrodynamic torque converter wherein a minimum slip is establishedindependently between the engine and the output of the torquetransmission system in dependency upon the torque division factor K_(ME)and deviations from the ideal condition are adoptively detected,processed and compensated for long-term.

[0025] A further embodiment of the method according to the inventionproposes that the torque transmittable by the torque transmission systembe controlled as a function of a driving torque so that in the case ofsystems without load distribution, such as a friction clutch and/or astarting clutch and/or a turning set clutch and/or a torque transmissionsystem of an automatic gearbox or an infinitely adjustable gearbox, suchas a cone pulley belt contact gearbox, the torque which can betransmitted by the friction clutch or starting clutch

M _(KSoll) =K _(ME) *M _(AN)

[0026] is ascertained and a definite overpressing of the torquetransmitting parts is carried out for K_(ME)≧1.

[0027] Furthermore, it can be advantageous if the torque which can betransmitted by a torque transmission system is varied as a function of adriving torque in such a way that in the case of systems without loaddistribution, such as a friction clutch and/or a starter clutch and/or atorque transfer system of an automatic gearbox and/or an infinitelyadjustable cone pulley belt contact gearbox, the torque which can betransmitted by the torque transmission system

M _(KSoll) =K _(ME) *M _(AN) +M _(Sicher)

[0028] is ascertained and for K_(ME)<1 a fictitious load distribution isreconstructed through a supporting control loop to be a copy of thebehavior of a parallel-connected torque transmission system, such as ahydrodynamic torque converter, and a proportion of the transmittabletorque is transmitted through the torque control and the remainingtorque is subsequently transmitted in dependency upon slip through asafety torque M_(Sicher).

[0029] Furthermore, it can be advantageous if the safety torqueM_(Sicher) is selected in dependency upon each operating point.

[0030] Similarly, it can be advantageous if the safety torque M_(Sicher)is ascertained and/or controlled in functional dependency upon the slipΔn or the throttle valve position d according to

M_(sicher) =f(Δn, d).

[0031] Similarly, it can be expedient if the safety torque M_(Sicher) isascertained and/or controlled in accordance with

M_(Sicher)=const.*Δn.

[0032] Furthermore, it can be advantageous if the torque division factorK_(ME) is constant within the entire operating range of the power train.

[0033] Similarly, it can be advantageous if the torque division orbranching off factor K_(ME) assumes an individual value which isascertained for each operating point and/or assumes at least in aportion of the operating range a relevant constant value each time; thevalues set in different portions of the operating range can bedifferent.

[0034] In this manner, it is advantageously possible to divide theentire operating range into partial ranges wherein, in each partialrange, the K_(ME) value is kept constant and the constant K_(ME) valuecan vary from operating range to operating range.

[0035] Furthermore, it may be advantageous if the value of the torquedivision factor K_(ME) is in functional relationship dependent upon theinput RPM and/or the vehicle speed.

[0036] In accordance with the inventive concept, it can be advantageousif the value of the torque division factor K_(ME) is dependentexclusively upon the speed of the driving aggregate.

[0037] It can be equally advantageous if the value of the torquedivision factor is dependent, at least in a portion of the entireoperating range, both upon the RPM and upon the input torque of thedriving aggregate.

[0038] Furthermore, it may be advantageous if the value of the torquedivision factor K_(ME) is dependent not only upon the output RPM butalso upon the torque of the driving aggregate.

[0039] Furthermore, it can be advantageous if a certain desired clutchtorque is transmitted by the torque transmission system substantially ateach point in time. It can thereby be expedient if the transmittableclutch torque follows the existing torque.

[0040] Such embodiment exhibits the advantage that the contact pressureof the torque transmission system need not be maintained permanently atthe highest value. According to the teaching of prior art, a torquetransmission system (such as a clutch) is acted upon by a multiple ofthe nominal engine torque.

[0041] In an automated torque transmission system, the following of thetransmittable torque entails that the setting device or actor not onlyinitiates the opening and closing processes during switching andstarting but that the setting device selects the transmittable torque ateach operating point to a value which corresponds at least substantiallyto the desired value.

[0042] In order that the setting device or actor need not be constantlyactive during follow-up, it may be expedient if the torque which can betransmitted by the torque transmission system is controlled with anoverpressure and the overpressure lies within a narrow scatter band inrelation to the desired value.

[0043] It can be expedient if the overpressure AM is dependent upon theoperating point.

[0044] It can be particularly advantageous if the operating range isdivided into partial ranges and the contact pressure and/or the maximumoverpressure is fixed for each partial range.

[0045] In accordance with a further embodiment of the invention, it maybe advantageous if the application of the contact pressure and/or of theoverpressure and/or of the transmittable clutch torque is variable intime.

[0046] Similarly, according to the inventive concept, it may beadvantageous if the transmittable clutch torque which is to be selecteddoes not drop below a minimum value M_(Min). The minimum torque candepend upon the operating point and/or upon the momentary operatingrange and/or upon the time.

[0047] Furthermore, the torque follow-up can be carried out by acombination of a time-variable follow-up with a minimum value whichfollow-up is specific to the operating point.

[0048] According to the inventive concept, it can be advantageous if anoperating point or the existing operating condition of a torquetransmission system and/or of a combustion engine is ascertained on thebasis of condition values determined or calculated from measurementsignals, such as in dependency upon the engine RPM and the throttlevalve angle, in dependency upon the engine RPM and the fuel throughput,in dependency upon the engine RPM and the inlet manifold underpressure,in dependency upon the engine RPM and the injection time or independency upon the temperature and/or friction value and/or slip and/orthe load lever and/or the load lever gradient.

[0049] In a torque transmission system with a combustion engine mountedat the input side, it is of advantage if the input torque of thecombustion engine can be determined from at least one of the conditionvalues of the operating point, such as the engine RPM, throttle valveangle, fuel throughput, inlet manifold underpressure, injection time ortemperature.

[0050] Still another embodiment of the method proposes that the torqueM_(AN)*K_(ME) which is applied at the input side of the torquetransmission system is influenced and/or altered with a dependencytaking into account the dynamics of the system, the dynamics of thesystem being adapted to be caused by the dynamic behavior as a result ofthe mass moment of inertia and/or free angles and/or damping elements.

[0051] It can be advantageous to provide means which purposefullyrestrict or influence the dynamics of the system.

[0052] Similarly, it can be advantageous if the dynamics of the systemare realized to influence M_(AN)*K_(ME) in a form corresponding to thatof gradient restriction.

[0053] The gradient restriction can be realized as a limitation of apermissible increment.

[0054] Furthermore, it can be advantageous if the gradient restrictionis realized in that the time-dependent change and/or the time-dependentincreased intensity of a signal is compared with the maximum permittedslope or slope function and, when the maximum permissible increment isexceeded, the signal is replaced with a substitute signal which isincremented with a previously defined slope.

[0055] Furthermore, it can be advantageous if the influencing orrestriction of the dynamics of the system is set up according to theprinciple of a timely dynamic and/or variable filter wherein thecharacteristic time constants and/or amplifications are time variableand/or dependent upon the operating point.

[0056] Advantageously, the dynamics of the system are taken into accountand/or processed with a PT₁ filter.

[0057] It can likewise be advantageous if the dynamics of the system arecharacterized by a maximum restriction wherein, when a certain thresholdvalue is exceeded, the desired value is represented by the thresholdvalue and, consequently, the desired value does not exceed a maximumvalue which is represented by the threshold value.

[0058] Furthermore, it can be advantageous to connect in series at leasttwo means for controlling the system, such as a gradient restriction anda filter stage.

[0059] It can likewise be advantageous to connect in parallel at leasttwo means for influencing the dynamics of the system, such as a gradientrestriction and a filter.

[0060] It is particularly advantageous if the dynamics of the combustionengine and the dynamics of the secondary consumers which cause a loaddistribution are taken into account when determining the driving torqueM_(AN). In such instances, it is especially advantageous if the massmoments of inertia of the utilized flywheel masses and/or elements areresorted to in order to take into account the dynamics of the combustionengine.

[0061] It can likewise be advantageous if the injection behavior of thecombustion engine is relied upon and/or forms the basis for theconsideration of the dynamics of the combustion engine.

[0062] It is likewise within the scope of the controlling methodaccording to the invention to compensate for deviations from the idealstate long-term by taking into consideration the secondary consumersand/or the correction and/or the compensation for disturbances and/orsources of disturbances.

[0063] It can be advantageous if the torque being applied at the inputside of the torque transmission system is detected and/or calculated asa difference between the engine torque M_(mot) and the sum of thetorques taken up or branched off by the secondary consumers. Forexample, the secondary consumers to be considered can include theclimate control and/or the dynamo and/or the servo pumps and/or thesteering aid pumps.

[0064] According to the inventive concept, it can be advantageous ifsystem condition values, such as the engine RPM and the throttle valveangle, the engine RPM and the fuel throughput, the engine RPM and theinlet manifold underpressure, the engine RPM and the injection time, theengine RPM and the load lever are used to determine the value of theengine torque M_(mot).

[0065] Furthermore, it can be advantageous if system condition valuesare relied upon to ascertain the engine torque M_(mot) from acharacteristic field of the engine. Analogously, it can be advantageousif system condition values are used to determine the engine torqueM_(mot) and the engine torque is determined through the solution of atleast one equation or an equation system. The solution of the equationor the equation system can be carried out numerically and/or can beascertained from the characteristic field data.

[0066] Furthermore, it can be advantageous if the torque takeup resp.the load distribution of the secondary consumers is determined frommeasured values, such as voltage and/or current measured values of thedynamo and/or switch-on signals of the relevant secondary consumersand/or other signals indicating the operating condition of the secondaryconsumers.

[0067] Furthermore, it can be advantageous if the torque takeup of thesecondary consumers is determined by means of measured values from thecharacteristic fields of the relevant secondary consumers. Likewise, thetorque takeup of the secondary consumers can be determined by solving atleast one equation or an equation system.

[0068] According to the inventive concept, it can be expedient if thecorrected transmittable clutch torque can be determined according to thetorque equation

M _(KSoll) =K _(ME)(M _(AN) −M _(Korr))+M _(Sicher)

[0069] and the correction torque M_(Korr) is obtained from a correctionvalue which is dependent upon the sum of torques taken up or branchedoff by the secondary aggregates.

[0070] Furthermore, it can be advantageous if a correction is carriedout for disturbances or breakdowns which influence measurable systeminput values.

[0071] It can be particularly advantageous for the novel method ifmeasurable disturbance factors are detected and/or identified and are atleast partially compensated for and/or corrected through a parameteradaption and/or a system adaption. Furthermore, it can be advantageousif one utilizes measurable system input values in order to identifydisturbance or breakdown values and/or to correct and/or to compensateat least partially for such values through parameter adaption and/orsystem adaption.

[0072] In order to identify a disturbance value and/or to correct thesame by means of a parameter adaption and/or system adaption and/or tocompensate for the same, at least in part, it is possible to use asparameters certain system input values such as for example temperatures,RPM, friction value and/or slip.

[0073] It can be particularly advantageous for the method if acompensation and/or correction of measurable disturbance factors iscarried out through adaption of the characteristic field of the engine.

[0074] In such instances, it may very well be the case that one observesor registers a disturbance or breakdown value which need not be causallyconnected with the characteristic field of the engine but a correctionof such disturbance value through an adaption of the characteristicfield of the engine can be advantageous. In such instance, the cause ofthe disturbance is not corrected or compensated for.

[0075] Furthermore, it can be of advantage if a correction field ofcharacteristic lines is established on the basis of a comparison betweenthe desired clutch torque and the actual clutch torque, and a correctionvalue is or can be ascertained for each operating point; such correctionvalue is linked, additively and/or multiplicatively, with the value ofthe engine torque from the characteristic field of the engine.

[0076] Furthermore, it can be particularly expedient if, in view of adeviation detected at an operating point between the desired value andthe actual value, analyses and/or undertakings are introduced in orderto calculate and/or establish deviations and/or correction values atother operating points of the entire operating range.

[0077] Furthermore, it can be advantageous if, in the light of adeviation detected at an operating point, one introduces analyses and/ormeasures in order to calculate or establish deviations and/or correctionvalues at other operating points of a limited operating range. Asconcerns the method, it can be of advantage if the limited operatingranges are set up in dependency upon the characteristic field.

[0078] Advantageously, an embodiment of the invention can becharacterized in that the analyses and/or undertakings for thedetermination and/or calculation of deviations and correction values atthe additional operating points take into account the entire operatingrange or a restricted operating range.

[0079] Furthermore, it can be advantageous if the analyses and/orundertakings for the calculation of deviations and/or correction valuesat the further operating points embrace only partial areas around theactual operating point. It can be particularly advantageous if theanalyses and/or undertakings for the determination and/or calculation ofdeviations and/or correction values are carried out at the furtheroperating points in such a way that weighting factors evaluate oremphasize different portions of the entire operating range in differentways.

[0080] It can be advantageous if the weighting factors are selectedand/or calculated as a function of the operating point. It can likewisebe advantageous if the weighting factors can depend upon the type of thedisturbance or breakdown value and/or upon the cause of the breakdown.

[0081] Furthermore, it can be particularly advantageous if, uponcompleted determination of the correction value and/or subsequent toweighting of the characteristic correction field, a time behavior isimpressed upon the correction value. For example, such time behavior maytake into account the dynamic behavior of the system.

[0082] It can be advantageous if the time behavior is determined througha pulse frequency, a scanning of the correction value and/or if the timebehavior is determined by at least one digital and/or analog filter.

[0083] It can be particularly advantageous in an embodiment of theinvention if the time behavior is varied for different breakdown valuesand/or different breakdown sources, namely in the event of using arelevant filter the parameters of the filter are set in dependency uponthe nature and the manner of action of the breakdown source. Thus, thetime constants and amplifications of the filters conform to therespective breakdown sources in order to guarantee an at leastsubstantially optimal adaption.

[0084] It can be advantageous if the time behavior is selected independency upon the value of the corrections. It can be particularlyadvantageous if the driving torque is adapted with an adaption methodwith greater or smaller time constant than the time constant of theadaption method of the clutch torque. It is advantageous if the timeconstant is within a range of between 1 second and 500 seconds, butpreferably within a range of between 10 seconds and 60 seconds and mostpreferably within a range of between 20 seconds and 40 seconds.

[0085] In accordance with a further embodiment, it can be expedient ifthe time constant is dependent upon the operating point and/or if thetime constant is selected and/or ascertained differently for differentoperating ranges. Furthermore, it can be of advantage if a compensationfor and/or correction of measurable breakdown values is carried outthrough adaption of the inverse transfer function of the transmissionunit with setting member.

[0086] A further advantageous embodiment of the method provides thatindirectly measurable breakdown values, such as especially the agingand/or straying of individual component parts of the torque transmissionsystem are detected in that some characteristic values of the torquetransmission system are monitored and the actually disturbed parametersare detected and corrected in dependency upon such monitoring and/orvirtual breakdown sources can be put to use in the form of programmodules in order to correct and/or compensate for the influence of thebreakdown values.

[0087] Furthermore, it can be advantageous if disturbances fromnon-measurable influence values, the straying of individual componentparts and/or the aging are detected and/or compensated for throughdeviations from condition values of the system. Furthermore, it can beadvantageous if disturbances or breakdowns, such as straying or aging orother non-measurable influence values, are not detected from measurableinput values but are recognized only by observing reactions of thesystem.

[0088] It can likewise be advantageous if the deviations from systemcondition values or condition values and/or observations of systemreactions are measured directly and/or calculated from other measuredvalues in a method model. It can likewise be advantageous to carry outthe detection of deviations from calculated method models by resortingto characteristic reference fields and/or unequivocal characteristicreference values of the system.

[0089] Another advantageous further development of the inventionprovides that, for the correction and/or for the compensation of adetected disturbance or breakdown from non-measurable input values abreakdown source be localized and/or a breakdown source be fixed and thedeviations at these breakdown sources be corrected and/or compensatedfor. Furthermore, it can be expedient if, for the correction of and/orfor the compensation for a detected breakdown, one fixes a fictionalbreakdown source which need not have a causal connection with thebreakdown and at which the detected deviation is corrected.

[0090] Advantageously, the fixed breakdown source can be an actuallyexisting function block and/or the fixed breakdown source can constitutea virtual breakdown model whilst preserving the correcting action.

[0091] According to a further development of the invention, the timelyprogress of the actual clutch torque is monitored and analyzed toascertain whether conclusions regarding the type of error and/or thedetection of the breakdown source and/or the localization of thebreakdown source can be arrived at.

[0092] Furthermore, it can be advantageous to permanently carry out theadaptive correction of the breakdown value.

[0093] A further advantageous embodiment proposes that the adaptivecorrection of the breakdown values be carried out only at certainoperating points and/or within certain operating ranges and/or timeranges.

[0094] Furthermore, it can be advantageous if the adaption can be activewhen the control is inactive. In this context, “inactive” can denotethat the control does not engage in or cause or carry out any activityof the setting member since, for example, an operating range is selectedor actually exists in which a torque follow-up is not carried out but,instead, a stationary value is set. In this operating range, one cancarry out an adaption of the parameter without carrying out an activecontrol.

[0095] Furthermore, it can be advantageous if the adaption is notcarried out within special operational ranges, especially in the eventof pronounced acceleration.

[0096] It can be expedient if, within the operating ranges of inactiveadaption, one utilizes correction values of the setting values whichwere detected within the previously determined operating ranges ofactive adaption. Furthermore, for such procedure, it may be expedient ifthe previously detected values for an adaption are stored in anintermediate memory and can be addressed in situations of a deactivatedadaption.

[0097] In a further embodiment of the invention, it may be expedient if,within the operating ranges of inactive adaption, one applies correctionvalues of the breakdown values which can be extrapolated with activeadaption from correction values in previously detected operating ranges.

[0098] In accordance with a further method according to the invention,it can be expedient if one adopts virtual breakdown models and/orvirtual breakdown values for the areas of the engine torque and/or forthe area of the net engine torque, after taking into account thesecondary consumers,and/or for the desired clutch torque.

[0099] Furthermore, it can be advantageous if one introduces and/oremploys the inverse transfer function of the transmitting unit withsetting member as a virtual breakdown source.

[0100] Furthermore, it can be expedient if the characteristic field ofthe engine is used as the virtual breakdown source.

[0101] It is particularly advantageous if virtual breakdown sources areused to define breakdown values whose original causes cannot belocalized, such as for example straying in the region of manufacturingtolerances of the individual component parts.

[0102] A further novel concept of the invention relates to a method ofcontrolling a torque transmission system with or without loaddistribution wherein the clutch torque adapted to be transmitted from aninput side to an output side of the torque transmission system is usedas a control value and such control value is put to use by means of asetting member to which is assigned a setting value which isfunctionally dependent upon the transmittable clutch torque, so that thetransmittable clutch torque always lies within a predetermined toleranceband around the slip limit, and the slip limit is reached at the exacttime when the action of the torque developing at the input side exceedsthat clutch torque which can be transmitted by the torque transmittingparts.

[0103] Furthermore, it can be advantageous if the setting member isassigned as a setting value a value which corresponds to the clutchtorque adapted to be transmitted between the torque transmitting partsof the torque transmission system.

[0104] A further expedient development of the invention proposes thatthe setting value be determined in dependency upon a transmittableclutch torque and that, in order to calculate such transmittable clutchtorque, one establishes a difference between the value of the drivingtorque and a correction value wherein the correction value is increasedor reduced in dependency upon at least one condition value of the torquetransmission system.

[0105] Furthermore, it can be expedient if the correction value isdetermined in dependency upon a differential RPM between an input RPMand an output RPM, designated slip RPM, the correction value beingincreased as long as the slip RPM is below a predetermined thresholdslip value and the correction value being reduced as long as the slipRPM is above such or another predetermined threshold slip value.

[0106] Furthermore, it can be of advantage if the correction values areincreased incrementally as long as the slip RPM is below the onethreshold slip value and the correction value is reduced stepwise aslong as the slip RPM is above the one or another threshold slip value.Stopping phases of adjustable length are provided between the relevantstages and, during each stopping stage, the correction value is keptconstant at a value set at the outset of each stopping stage.

[0107] Furthermore, it can be advantageous if the times during which theinput RPM exceeds the output RPM by a defined slip RPM are recognized asthe slip phase and at the end of each slip phase the correction value isset again to a definite value.

[0108] An advantageous embodiment of the invention proposes that thetimes during which the input RPM exceeds the output RPM by a definiteslip RPM be recognized as slip phases, and that the relevant correctionvalue at which the slip RPM assumes its maximum value be stored in anintermediate memory and at the end of a slip phase the actual correctionvalue be again replaced by the stored correction value.

[0109] It can likewise be advantageous if the correction value be keptconstant at its relevant value for a fixable interval of time at the endof each slip phase. According to another embodiment of the invention, itcan be advantageous if the setting member is assigned a preset value independency upon a characteristic field or a characteristic line whichembraces the area of all transmissible clutch torques or has at leastone partial area within which only one preset value is allocated for thesetting member for all transmissible clutch torques.

[0110] Furthermore, it can be advantageous that, in order to calculatethe transmissible clutch torque, one forms a difference between an inputtorque value and the correction value, and this difference is increasedby a torque value which is dependent upon slip.

[0111] According to a further embodiment of the invention, it may be ofadvantage if the rise of the actual clutch torque is restricted in theform of a gradient restriction in that the relevant actual value of thetransmissible clutch torque is compared with a comparison torque valuewhich consists of a previously detected transmissible clutch torquevalue and an additive fixable limiting value and that, in dependencyupon such comparison, the smaller torque value is assigned to thesetting member as the new preset value.

[0112] It can be particularly advantageous if several condition values,such as for example the engine RPM, throttle valve angle and/or suctionintake pressure, are ascertained from a combustion engine mounted at theinput side of the torque transmission system and the input torque of thecombustion engine is detected from these condition values by means ofstored characteristic lines or characteristic line fields. Furthermore,the invention proposes that eventual branchings of output between thedrive and the torque transmission system be monitored at least partiallyor at least temporarily and the thus obtained measured values be used tocalculate the input torque actually arising at the input side of thetorque transmission system.

[0113] It can be advantageous if each time a part of the input torquecorresponding to a proportion factor be used to calculate thetransmissible clutch torque and if such proportion factor is determinedeach time from the stored characteristic line fields or characteristiclines.

[0114] Furthermore, it can be expedient if, with torque transmissionsystems without load distribution, a load distribution is reconstructedthrough a slave control program.

[0115] According to the inventive concept, it can be advantageous ifmeasurable breakdown values, such as in particular temperatures and/orRPM, are detected and are compensated for at least partially through aparameter adaption and/or through a system adaption.

[0116] An expedient further development proposes that indirectlymeasurable breakdown values of the control method, such as in particularaging and/or straying of individual component parts of the torquetransmission system, be detected by monitoring some condition values ofthe torque transmission system and, in dependency upon such monitoring,the actually affected parameters are recognized and corrected and/orvirtual breakdown sources which can be switched on in the form ofprogram modules are used in order to correct and/or compensate for theinfluence of the breakdown values.

[0117] Furthermore, it can be advantageous if a first engagement of theclutch is made possible only subsequent to checking of the authority ofthe user.

[0118] It can likewise be advantageous if a display, such as a userdisplay, is controlled in dependency upon the status of the controlmethod in such a way that a switching recommendation is given for theuser. This switching recommendation can be carried out through thedisplay in an optical manner or, alternatively, in an acoustic manner.

[0119] It can also be advantageous if phases of idleness, particularlyof a vehicle, are recognized by monitoring significant operating values,such as accelerator pedal and/or gear linkage position and/or tacho RPMand, upon elapse of a defined time period, the driving unit is arrestedand restarted when necessary.

[0120] Furthermore, it can be advantageous if operating phases of thetorque transmission system with minimal or without load takeoff arerecognized as freewheel phases and if the clutch is disengaged duringsuch freewheel phases and is reengaged at the end of the freewheelphase. The end of the freewheel phase can take place or can berecognized, for example, through a detected change of the position ofthe load lever and/or of the load lever gradient.

[0121] According to a further embodiment of the invention, anantiblocking system can be assisted by applying the control method insuch a way that, when the ABS system is active, the clutch is completelydisengaged.

[0122] Furthermore, it can be advantageous if the setting member iscontrolled within certain operating ranges after actuation of theantislip control.

[0123] The invention not only relates to the aforedescribed method ofcontrolling a torque transmission system but also relates especially toa torque transmission system for the transmission of torque from aninput side to an output side wherein an internal combustion engine, suchas a motor, is disposed at the input side and a gearbox is disposed atthe output side and the torque transmission system has a clutch, asetting member and a control device.

[0124] Furthermore, the invention relates to a torque transmissionsystem which can be controlled by means of the method described aboveand serves to transmit torque from an input side to an output side,wherein the output of the torque transmission system is connected in thepower flow of a driving unit, such as a combustion engine, and avariable-transmission device, such as a gearbox, is installed in thepower flow at the upstream or at the downstream side, and the torquetransmission system comprises or contains a clutch and/or a torqueconverter with lockup clutch and/or a starting clutch and/or a turningset clutch and/or a safety clutch for limiting the transmissible torque,a setting member and a control device.

[0125] According to the inventive concept, particularly advantageous ifthe clutch is a self-adjusting or self resetting clutch.

[0126] It can be equally advantageous if the clutch automaticallyadjusts or compensates for wear, for example, upon the friction linings.

[0127] According to the inventive concept, it can be of advantage inactual practice of the invention if, in order to transmit the torquefrom an input side to an output side, the torque transmission systemhave a clutch, a setting member and a control unit wherein the clutch isoperatively connected with the setting member through a hydraulicconduit which contains a slave clutch cylinder and the setting member isactuated by the control unit.

[0128] A further advantage resides in the utilization of a settingmember having an electric motor which acts through an eccentric upon ahydraulic master cylinder which is attached to the hydraulic conduitwhich, in turn, is connected to the clutch, a clutch path sensor beingmounted in the housing of the setting member.

[0129] In order to achieve a compact and flexible solution for thearrangement of the device according to the invention, it is advantageousif the electric motor, the eccentric, the master cylinder, the clutchpath sensor and the required control and load electronics are mounted inthe housing of the setting member.

[0130] It can likewise be of advantage if the axes of the electric motorand of the master cylinder are mounted to extend in parallelism witheach other. It is particularly advantageous if the axes of the electricmotor and of the master cylinder are mounted to extend in parallelismwith each other in two different planes and are operatively connected toeach other by the eccentric.

[0131] It can furthermore be of advantage if the axis of the electricmotor extends in parallelism with a plane which is formed essentially bythe board of the control and output electronics.

[0132] According to a further development of the novel torquetransmission system, the mode of operation of the transmission systemcan be optimized by mounting a spring concentrically with the axis ofthe master cylinder in the housing for the setting member.

[0133] Furthermore, it can be advantageous if a spring is mounted in thehousing of the master cylinder concentrically with the axis of themaster cylinder.

[0134] It can be advantageous for the functioning of the apparatusaccording to the invention if a characteristic curve of the spring isselected in such a way that the maximum force to be applied by theelectric motor to engage and disengage the clutch is approximately thesame in the pull and push directions.

[0135] Furthermore, it can be advantageous if the characteristic curveof the spring is designed in such a way that the resulting progress ofthe forces acting upon the clutch is linearized during disengagement andengagement of the clutch. According to a further development, the powerrequirement and thus the size of the electric motor is minimized. Thoseforces which are required for the disengagement of the clutch aredecisive for the dimensioning of the electric motor to be used since agreater force is needed for the disengagement than for the engagement ofthe clutch because the force of the spring assists the disengagementand, therefore, one can use a weaker electric motor.

[0136] By using a spring within the master cylinder piston, noadditional space is required for the spring.

[0137] Furthermore, it can be of advantage if the electric motor havinga motor output shaft acts upon a segment wheel through a worm and thesegment wheel carries a crank which is operatively connected with thepiston of the master cylinder by a piston rod in such a way that it ispossible to transmit pushing and pulling forces.

[0138] It can likewise be of advantage if the worm and the segment wheelconstitute a self-locking transmission.

[0139] The invention does not, however, relate only to theaforedescribed method of controlling a torque transmission system and tothe torque transmission system itself, but also encompasses a monitoringmethod for a torque transmission system with a manually actuatablegearbox, wherein relevant gear lever positions and an input torque of adriving unit at the input side are detected with a sensor system and atleast one corresponding gear lever signal and at least one comparisonsignal are recorded and different possible characteristics of theprogress of these signals, such as for example a difference, arerecognized and identified as the switching intention and a switchingintention signal is then transmitted to a clutch operating system at theoutput side.

[0140] As concerns the inventive concept, it can be advantageous if atleast one progress of the gear lever signal is evaluated to detect theselected gear and such information is used to identify a switchingintention.

[0141] The monitoring method ascertains the gear which is engaged atthat time, and such information can be used to determine the comparisonsignal.

[0142] In this manner, one provides a method with which an eventualswitching intention of the user is recognized at a high speed and in ahighly reliable manner without it being necessary to use a specificsensor. A predominantly automated torque transmission system requiresearly information regarding a possible switching intention in order todisengage the clutch in good time.

[0143] It can be advantageous if a gear lever signal and a comparisonsignal are evaluated in such a way that intersecting points of thesesignal paths are detected and then a switching intention signal istransmitted to the clutch operating system at the output side. If, inorder to detect the switching intention, only two signal paths areinvestigated or evaluated for intersecting points, there is no longerany need for expensive software or hardware.

[0144] According to the inventive concept, it can be advantageous if,with the switching gearbox, a selection path is differentiated betweenthe switching lanes and a switching path within the switching lanes. Theswitching path and/or the selection path can be monitored in order todetermine the relevant gear lever position.

[0145] Also, there is no need for additional sensor systems for thegeneration of the comparison signal since, as a rule, the single inputvalue (namely the input torque) can already be determined. Since thecomparison signal is formed from a filter signal wherein the filtersignal is intensified and/or weakened by a constant value and an offsetsignal, it is practically ensured that the gear lever signal and thecomparison signal intersect only if a switching intention actuallyexists.

[0146] In accordance with an advantageous further development, theexistence of a switching intention is detected during monitoring of thetwo signal paths of the gear lever signal and the comparison signal ifan intersection point is detected and, at such time, the switchingintention is verified by means of a switching intention counter. Withthe claimed switching intention counter, one ensures that a definiteinterval of time elapses between the realization of the switchingintention and the transmission of the switching intention signal, andsuch interval of time suffices to ascertain whether a switchingoperation is actually initiated. In this manner, the torque transmissionsystem is effectively protected against an unintentional release.

[0147] The gear lever signal is filtered with an adjustable time delayin order to generate a filter signal.

[0148] It can be particularly advantageous if the gear lever signal canbe processed to form the filter signal with a PT1 characteristic.

[0149] Furthermore, it can be advantageous if the gear lever signal ismonitored and a change of the switching path within a defined portion ofthe gear lever path is evaluated within a fixable measuring period insuch a way that a switching intention signal is transmitted to devicesat the output side when a fixable switching path change threshold is notreached.

[0150] The gear lever signal, which is used to ascertain the existenceof a switching intention, which in turn is passed on, can be tuned bymeans of individually adjustable filters, which are universally usablethrough filter parameters, in such a way that a wide variety of torquetransmission systems can be monitored by resorting to the same method.It is advantageous if the measuring period is fixed in such a way thatit is always clearly greater than a half vibration period resp.vibration amplitude of the gear lever which is not actuated duringoperation of the vehicle.

[0151] It can be expedient if the defined portion of the gear lever pathis outside of the gear lever path areas within which the non-operatedgear lever moves when the vehicle is in operation.

[0152] In order to practice the method according to the invention, it isnecessary as a rule to average the gear lever vibration periods. In thismanner, the duration of the measuring period can be fixed in dependencyupon the formation of average value of the gear lever vibration period.

[0153] In accordance with a further development, one can ascertainwhether the gear lever vibrates freely during operation of the vehicleor has a different vibration behavior, especially when a hand is placedthereon. The mean value formation to determine the length of themeasuring periods is carried out in dependency upon the results of suchmonitoring.

[0154] According to a further development of the invention, it can beadvantageous if the direction of movement of the gear lever is detectedand when such direction of movement is reversed, a control signal istransmitted to the switching intention counter and/or an alreadytransmitted switching intention signal is rescinded.

[0155] In this manner, the direction of movement of the gear lever isadditionally observed and a reversal of such direction of movemententails a rescinding of a switching intention signal which wouldotherwise be transmitted as a result of vibration of the gear lever.

[0156] Furthermore, it can be advantageous if the constant value for thegeneration of the comparison signal is selected in dependency upon thetypical operating vibration amplitude of the non-operated gear lever ofthe torque transmission system.

[0157] It can likewise be advantageous if the delay time with which thefilter signal is generated is caused to conform to the vibrationfrequency of the gear lever which is not actuated during operation ofthe vehicle.

[0158] In accordance with the inventive concept, it can be particularlyadvantageous for a control method if the driving load is monitored and,on exceeding a fixable driving load, a control signal is transmitted tothe switching intention counter. In this manner, one can prevent that,in the event of an increased torque at the engine side, the clutch isunintentionally disengaged or engaged. It can likewise be advantageousif the offset signal is applied in dependency upon the relevant throttlevalve angle in a combustion engine which is used as the driving unit.

[0159] In accordance with the inventive concept, it is expedient if theswitching or selection path of the gear lever is ascertained by apotentiometer. It can likewise be advantageous if the switching and/orselection path of the gear lever is ascertained by a potentiometer insuch a way that the gear setting can be recognized by the potentiometer.

[0160] However, the invention does not relate only to the aforediscussedmethod of controlling a torque transmission system but also encompassesthose processes for controlling a torque transmission system having adevice for controlling the torque transmission system, the torquetransmission system is mounted at the output side in the power flow of adriving unit and at the input and/or output side in the power flow of avariable transmission device, the variable transmission device beingprovided with endless flexible means which transmit torque from a firstmeans to a second means, the first means being operatively connectedwith the input shaft of a gearbox and the second means being operativelyconnected with an output shaft of the gearbox, the endless flexiblemeans is in frictional contact with the first and the second meansthrough contact pressure or tensioning and the contact pressure ortensioning of the endless flexible means being controlled in dependencyupon the operating point, characterized in that the torque transmissionsystem is started with follow-up torque, namely with a transmissibletorque which is dimensioned at each operating point in such a way thatthe endless flexible means of the variable transmission device does notbegin to slip. This means that the slip limit of the torque transmissionsystem is controlled at each operating point so that the slip limit ofthe endless flexible means is always greater and if the applied torqueis excessive, the torque transmission system always begins to slipbefore the endless flexible means slips.

[0161] Furthermore, it can be advantageous if the contact pressureand/or tensioning of the endless flexible means is determined andapplied at each operating point in dependency upon the applied enginetorque and/or the load distribution or branching off regarding thesecondary consumers and an additional safety tolerance and thetransmissible torque of the torque transmission system is controlled independency upon the operating point and the torque transmissible by thetorque transmission system entails, in the event of torque fluctuations,slippage of the torque transmission system before the slip limit of theendless flexible means is reached.

[0162] It is particularly expedient if the slip limit of the torquetransmission system at each operating point is lower than the slip limitof the endless flexible means of the variable transmission device.

[0163] In accordance with the novel concept, it can be of additionaladvantage if the torque transmission system with its slip limitdependent upon the operating point isolates and/or damps torquefluctuations and torque surges at the input side and/or at the outputside and protects the endless flexible means against slip. Thus, theendless flexible means is protected against slippage because theslippage under the above outlined circumstances could lead todestruction of the endless flexible means and thus to a breakdown of thegearbox.

[0164] According to the inventive concept, it is expedient to controlthe contact pressure or the tensioning of the endless flexible means independency upon the operating point and, in addition to the appliedtorque, to take into account a safe reserve which can be caused toapproximate and/or to conform to the transmissible torque through theselection of the transmissible torque of the torque transmission system.The adaptation of safety torque can be carried out in this case in sucha way that the selected safety reserve can be less than in accordancewith prior art proposals.

[0165] It can be particularly advantageous if the safety reserve of thecontact pressure or tensioning is as low as possible as a result ofprotection of the torque transmission system against slip.

[0166] It is particularly expedient if the torque transmission systemslips or slides only briefly in the event of torque surges. It is thuspossible to isolate or damp or filter torque surges at the input side orat the output side; such surges may occur in extreme driving situationsand could damage or destroy the endless flexible means.

[0167] The invention relates not only to the aforedescribed method butalso to an apparatus, such as a variable transmission device, which iscontrolled in accordance with the aforementioned method and wherein thevariable transmission device can be an infinitely adjustable gearbox. Itmay be especially advantageous if the variable transmission device is aninfinitely adjustable cone pulley belt contact gearbox. It can also beparticularly advantageous if the torque transmission system which ispart of the apparatus is a friction clutch or a converter lockup clutchor a turning set clutch or a safety clutch. The clutch can be a dryclutch or a wet clutch. Furthermore, it may be expedient to provide asetting member which controls the transmissible torque and is controlledelectrically and/or hydraulically and/or mechanically and/orpneumatically, or the actuation of the setting member is effected by acombination of these undertakings.

[0168] The invention does not relate only to the aforedescribed methodsbut especially also to an apparatus with at least one sensor for thedetection of the effective gear ratio or the engaged gear of a gearbox,a central computer unit being provided to process the sensor signals andto calculate the gearbox input speed. For such calculation, it isfurther necessary to take into consideration the transmission ratios,such as the transmission ratios of the differential.

[0169] It can be of advantage if the ascertained rotational speeds ofthe wheels are averaged and the thus obtained averaged signal isutilized to ascertain or to calculate the gearbox input RPM by takinginto consideration the transmissions in the power train and thetransmission ratio of the gearbox.

[0170] It is of advantage if the rotational speed of the wheels isascertained by utilizing one to four sensors, and is particularlyadvantageous if one employs 2 or 4 sensors.

[0171] The apparatus can be constructed in a particularly advantageousmanner and way if the sensors which serve to detect the rotationalspeeds of the wheels are in signal transmitting connection with theantiblocking system or constitute component parts of an antiblockingsystem.

[0172] The invention will be explained in greater detail with referenceto an embodiment in the vehicle industry.

BRIEF DESCRIPTION OF THE DRAWINGS

[0173] There are shown in:

[0174]FIG. 1a a block diagram of a torque transmission system with loaddistribution,

[0175]FIG. 1b a block diagram of a torque transmission system withoutload distribution wherein a fictitious load distribution is copiedthrough a slave control program,

[0176]FIG. 2a to 2 e diagrammatic illustrations of different physicalproperties of a torque transmission system as a function of the torquedivision factor K_(ME);

[0177]2 a: acoustics as a function of K_(ME);

[0178]2 b: thermal stressing as a function of K_(ME);

[0179]2 c: pulling force as a function of K_(ME);

[0180]2 d: fuel consumption as a function of K_(ME);

[0181]2 e: load change behavior as a function of K_(ME),

[0182]FIG. 3 a block diagram resp. a signal diagram of a control methodwith adaption,

[0183]FIG. 4 a block diagram resp. a signal diagram of a control methodwith adaption,

[0184]FIG. 5a to 5 c the effect of disturbance values upon the torque asa function of time; a: additive interference through, e.g., additionalaggregates; b: multiplicative interferences; c: additive disturbancevalues,

[0185]FIG. 6 a characteristic correction field of engine torque as afunction of the engine torque and the RPM,

[0186]FIG. 6a a diagrammatic illustration of a breaking up of acharacteristic field,

[0187]FIG. 6b a diagrammatic illustration of a breaking up of acharacteristic field,

[0188]FIG. 7 a block diagram for the control method with adaption,

[0189]FIG. 8 a block diagram for a control method with adaption,

[0190]FIG. 9 a block diagram for a control method with adaption,

[0191]FIG. 10 a diagrammatic illustration of a vehicle with a torquetransmission system,

[0192]FIG. 11a a longitudinal sectional view through a setting memberunit of a torque transmission system,

[0193]FIG. 11b a cross sectional view of the setting member unit at III,

[0194]FIG. 12a a longitudinal sectional view of a setting member unit ina torque transmission system,

[0195]FIG. 12b a cross sectional view of the setting member unit at IV,

[0196]FIG. 13 a force diagram showing the behavior of the settingmember,

[0197]FIG. 14 a diagram for the determination of a clutch torque,

[0198]FIG. 15 a characteristic line field for the determination of theposition of a setting member,

[0199]FIG. 15a to 15 e diagrams of the positioning of the setting memberas a function of time,

[0200]FIG. 16 a circuit diagram of a manual gearbox,

[0201]FIG. 17 a signal diagram for detecting the switching intention,

[0202]FIG. 18 a signal diagram for the generation of a comparisonsignal,

[0203]FIG. 19 a further signal diagram for ascertaining the switchingintention,

[0204]FIG. 20 a signal diagram for verification of the detection of theswitching intention,

[0205]FIG. 21 a functional diagram of an electrohydraulically controlledtorque transmission system,

[0206]FIG. 22 a characteristic curve,

[0207]FIG. 23 a block circuit diagram,

[0208]FIG. 24 the progress of a signal as a function of time,

[0209]FIG. 25 the progress of a signal as a function of time,

[0210]FIG. 26 the progress of a signal as a function of time,

[0211]FIG. 27 the progress of a signal as a function of time,

[0212]FIG. 28 a characteristic curve with support position adaption,

[0213]FIG. 29a a gearbox with a torque transmission system disposed atthe input side, and

[0214]FIG. 29b a gearbox with a torque transmission system disposed atthe output side.

[0215] Each of the FIGS. 1a and 1 b is a diagrammatic illustration of aportion of a power train in a vehicle wherein a driving torque is beingtransmitted by an engine 1 with a mass moment of inertia 2 to a torquetransmitting system 3. The torque which can be transmitted by the torquetransmitting system 3 can be transmitted, for example, to a downstreampart in a gearbox, such as an input part, and such part is not explainedin detail.

[0216]FIG. 1a is a diagrammatic illustration of a torque transmissionsystem 3 with load branching or distribution or splitting wherein, forexample, a Föttinger clutch or a hydrodynamic torque converter 3 a isdisposed in the power flow and is connected in parallel with a converterlockup clutch 3 b. A control unit regulates the operation of the torquetransmitting system 3 in such a way that, at least under certainoperating conditions, the applied torque is transmitted substantially inparallel, either only by the hydrodynamic torque converter 3 a, only bythe Fbttinger clutch or the converter lockup clutch 3 b, orsimultaneously by the two torque transmitting devices 3 a, 3 b.

[0217] In some of the operating ranges, it may be desirable to resort tointentionally transmittable torque between the selected parallel torquetransmission devices 3 a, 3 b and can be carried out accordingly. Theratio of the torque being transmitted, for example, by the converterlockup clutch 3 b and the hydrodynamic torque converter can be caused toconform to specific requirements within the individual operating ranges.

[0218]FIG. 1b is a diagrammatic illustration of a torque transmissionsystem 3 without load distribution. A torque transmission system 3 ofsuch kind without load distribution can constitute, for example, aclutch, such as a friction clutch and/or a turning set clutch and/or astarting clutch and/or a safety clutch. A slave control program copies afictitious load distribution and controls the torque transmission systemaccordingly.

[0219] The diagrammatic sketches or block diagrams which are shown inFIGS. 1a and 1 b and form part of a partially illustrated power train,with the torque transmitting system 3 mounted in the power flow at theinput side with or without load distribution, merely constitute examplesof possible arrangements or designs of torque transmission systems.

[0220] Furthermore, it is also possible to employ arrangements of torquetransmission systems wherein the selected torque transmission system canbe mounted in the power flow upstream or downstream of the componentpart or parts determining the transmission ratio of the gearbox. Thus,for example, a torque transmission system (such as a clutch) can bemounted in the power flow upstream or downstream of the variator of aninfinitely adjustable cone pulley belt contact gearbox.

[0221] An infinitely adjustable gearbox, such as an infinitelyadjustable cone pulley belt contact gearbox, can likewise be realizedwith a torque transmission system mounted at the input side or at theoutput side.

[0222] Systems with load distribution of the character shown in Figure1a, such as a hydrodynamic torque converter 3 a with lockup clutch 3 b,can be controlled by resorting to a control method according to theinvention in such a way that the torque which can be transmitted by theindividual parallel-connected torque transmission systems, such as thetorque converter 3 a and the lockup clutch 3 b, is adapted to be startedor controlled. As a rule, the transmission of torque to be transmittedby one of the two torque transmission systems which are arranged inparallel is started and the torque which is to be transmitted by thetorque transmission system connected in parallel therewith is setautomatically.

[0223] As a rule, in torque transmission systems with more (N) than twoparallel-connected transmission systems, the torques which can betransmitted must be controlled by (N-1) transmission systems and thetransmittable torque of the (N-th) transmission system is then setautomatically.

[0224] In systems without load distribution, such as, e.g., in afriction clutch, the transmission of torque can be initiated through acontrol loop, which underlies the control, in such a way that thecontrol simulates a system with fictitious load distribution. Thefriction clutch 3 c is adjusted by such control, e.g., to a desiredvalue which is less than 100% of the transmissible torque. Thedifference between the thus selected desired torque and the 100% of theentire transmittable torque is established by the controls through aslip-dependent safety clutch 3 d. In this manner, one ensures that, onthe one hand, the friction clutch is not engaged with a contact pressurehigher than that which would be necessary for the transmission of therequired torque and, on the other hand, due to the operation with slip,one can ensure a damping of torsional vibrations and peak values oftorque, such as surges of the torque in the power train.

[0225] Within another stage of the operating range of the torquetransmission system, it can be advantageous if the torque transmissionsystem (such as a friction clutch or another clutch) is engaged with alow but well-defined overpressure or excessive contact pressure. Withinthese operating ranges (e.g., at high rotational speeds), it is nowpossible to avoid pronounced slip and to thus also avoid excessiveconsumption of fuel by the internal combustion engine.

[0226] With a contact pressure at about 110% of the applied averagedtorque, it is possible to establish an intentional slip or sliding ofthe clutch in response to the development of short-lasting peak valuesof torque. Thus, a damping of the peak values can be achieved with asubstantially engaged clutch.

[0227] Furthermore, it is possible to damp or insulate surges of torquehaving peak values by operating the clutch with only slight overpressurein order to establish a short-lasting slip or sliding of the clutch.

[0228] That parameter which is characteristic of the division of torquebetween the parallel-connected torque transmission devices of the torquetransmission system 3 is the torque dividing factor K^(ME) which isdefined by the ratio of torque adapted to be transmitted by a clutch oranother torque transmission device (such as, e.g., a converter lockupclutch) to the entire torque which can be transmitted by the torquetransmission system.

[0229] The torque dividing or division factor KME thus indicates theratio of the transmissible torque, e.g., of that torque which can betransmitted by a clutch 3 b, to the overall transmissible torque.

[0230] When the value of K_(ME) is less than one, this indicates thatthe transmissible torque is divided between the parallel-connecteddevices 3 a, 3 b and the torque being actually transmitted by the device3 a or 3 b is less than the overall applied torque or the overall torqueto be transmitted.

[0231] When K_(ME)=1, the transmissible torque is being transmitted onlyby one of the parallel-connected devices 3 a, 3 b, especially by theclutch 3 b. If the torque develops temporary peaks with values which areabove the value of the transmissible torque, this can result in a slipor sliding of the clutch or of the torque transmission devices. However,if the operating range has no torque peaks, the entire torque is beingtransmitted by one of the devices 3 a, 3 b.

[0232] If the value of K_(ME) exceeds one, the entire applied torque islikewise transferred by one device; however, for example, the contactpressure of the clutch corresponds to a transmissible torque which isgreater than the applied torque. It is thus possible to filter offgreater torque irregularities which lie above a threshold value andslight torque irregularities are not filtered.

[0233] A further advantage of a defined overpressure, as opposed to thecompletely engaged clutch, is the shorter reaction time of the systemuntil, for example, the clutch is disengaged. The system need notdisengage the clutch from the completely engaged condition but only fromthe actually existing condition. However, a slightly slower actuator canbe used at the same interval of time.

[0234]FIGS. 2a to 2 e illustrate the behavior of physicalcharacteristics or physical values of torque transmission systems as afunction of the torque division factor K_(ME), with reference to ahydrodynamic torque converter with a converter lockup clutch. The plusand minus signs along the ordinates indicate more positive or morenegative influences of the KME factor upon the illustrated physicalproperties.

[0235]FIG. 2a shows the acoustic properties of the power train of amotor vehicle. The curves indicate the progress of torques beingtransmitted by a torque transmission system with a damper and theprogress of torque being transmitted by a torque transmission systemwithout a damper, as a function of K_(ME). The curves for the two torquetransmission systems, with and without damper, run parallel as afunction of K_(ME). The torque transmission system with a damper has aslightly improved quality regarding acoustics as compared with thetorque transmission system without a damper.

[0236] It can be seen that, as a function of the value of K_(ME), whenK_(ME)=0, the acoustics assume their most favorable value. Withincreasing K_(ME), the acoustic properties drop monotonously until, athigh K_(ME) values, the acoustic properties show a transition to a valuewhich is independent of K_(ME).

[0237] Such behavior of the acoustic properties in dependency upon thetorque division factor K_(ME) can be explained through the increaseduncoupling of the power train from the torque irregularities and torquepeaks of the driving aggregate as a result of an increase of slip as afunction of a reduced K_(ME) value.

[0238] With decreasing slip in the torque transmission system andincreasing K_(ME), the torque irregularities in the drive train aretransmitted more pronouncedly and the damping action is reducedsimultaneously until, at a certain K_(ME) value, the damping becomesminimal or no longer exists at all. Thus, a constant acoustic behaviorcan be arrived at as a function of a further rising K_(ME) value. TheK_(ME) value at which a constant acoustic behavior is established as afunction of the torque division factor is dependent upon the thenexisting characteristic of the power train. With characteristic systems,this value lies at about K_(ME)=2. At this value, the clutch of thetorque transmission system is engaged to such an extent that practicallyeach and every torque fluctuation is being transmitted.

[0239]FIG. 2b shows the thermal stressing of a hydrodynamic torqueconverter with a converter lockup clutch as a function of the K_(ME)value. The expression “thermal stressing” can denote, for example, theenergy input into the system as the result of friction or as the resultof different speeds of the component parts. More specifically, forexample, one can take into consideration the energy input in a torqueconverter or into the fluid of a torque converter. Likewise, such termcan denote the energy input into the friction faces of a converterlockup clutch and/or friction clutch.

[0240] The low value of the thermal stressing when K_(ME)=0 rises withan increased value of K_(ME). The expression “thermal stressing” isintended to denote, inter alia, the energy input as a result ofdifferences of RPM. With an increasing K_(ME), the energy inputdecreases as a result of speed differences in the converter until, whenK_(ME)=1, the converter lockup clutch is engaged and the RPM differencesequal zero; therefore, the thermal stressing assumes its most favorablevalue. For K_(ME)≧1, the thermal stressing is constant and equal to thevalue for K_(ME)=1.

[0241]FIG. 2c shows the change of the pulling force which decreases as afunction of a rising K_(ME) value since, at a low K_(ME); value, theconversion area of the torque converter is put to better use and/or thelow K_(ME) allows another, more favorable, operating point of theinternal combustion engine to be achieved.

[0242]FIG. 2d shows a fuel consumption which becomes more favorable asthe K_(ME) value rises. Owing to a reduced slip, for example, in therange of the hydrodynamic torque converter, it is possible for the fuelconsumption to be reduced with a clutch which becomes increasinglyengaged as the K_(ME) value rises.

[0243]FIG. 2e shows the load change behavior as a function of the K_(ME)value. The load change behavior is shown to be most satisfactory whenK_(ME)=1, i.e., with a clutch engaged in this manner, the torque whichcan be transmitted by the clutch corresponds exactly to the appliedtorque.

[0244]FIG. 3 is a diagrammatic illustration of a block circuit diagramof a control method. In this diagram, the setting member and the controlcircuit are denoted by a block 4. The control method 5 and the adaption6 (system adaption and/or parameter adaption) can likewise be denoted bycommon blocks.

[0245] The control path with a setting member, or a transmission unitwith a setting member 31, and the disturbances acting upon such systemare denoted by the block 4. A driving assembly 16, such as an internalcombustion engine or motor, transmits an engine torque M_(mot) 33 independency upon the input values 14, such as for example the quantity ofinjected fuel, load lever, RPM of the driving aggregate, etc. or thecharacteristic system values 32, such as temperature, etc. The enginetorque M_(mot) 33 is branched off in part through secondary consumers34, such as a dynamo, a climate control, servo pumps, steering aidpumps, etc. These secondary consumers are taken into account in theblock 35 by subtracting the branched off torque 34 a from the enginetorque 33 to arrive at a resulting net torque 36.

[0246] The dynamics of the engine 16 and/or power train such as, e.g. asa result of the mass moment of inertia of the flywheel, are consideredin the block 37. The dynamics can take into account especially themoments of inertia of the respective component parts and the effect ofsuch moments of inertia upon the net input torque. The torque M_(dyn)38, which is corrected in view of the dynamics of the system, istransmitted through a transmission unit with a setting member orselector 31 and is transmitted from there as the actual clutch torque 48to the gearbox or to the vehicle 39 connected to the output of thegearbox.

[0247] The transmission unit 31 with a setting member 31 is influencedby the values 40, such as the temperature, the friction coefficient ofthe friction linings, the rotational speeds (RPM), the slip, etc. Inaddition, the transmission unit like the motor 16 can be disturbedand/or influenced through tolerances, aging or interference(unanticipated undesirable influences) by influence values which cannotbe directly measured. Such influencing is represented by the block 41.

[0248] The adaption 6 can be divided basically into three areas. On theone hand, one takes into account the secondary consumers or secondaryassemblies 7, and the adaption strategies or adaption procedures relatedthereto are used in the adaption of the breakdown or disturbance valuesand the influence of such breakdown values. The secondary consumers caninclude the climate control, the dynamo, the steering aid pump, theservo pumps and additional secondary consumers which cause a division orbranching off of the torque.

[0249] In order to compensate for the secondary consumers 7, signals anddata 8 pertaining to these secondary consumers 7 are used in order to bein a position to determine and/or calculate the status of the secondaryconsumers 7. The status indicates, inter alia, whether a particularsecondary consumer branches off a torque because it is switched on orswitched off and, if it is switched on, how great the branched offtorque is at the corresponding point of time.

[0250]FIG. 3 makes it clear that, in addition to the secondary consumeradaption 7, the system adaption distinguishes between first and secondadaption loops 9, 11. The influences of measurable breakdown values 10are considered in the first adaption loop 9. The influences of onlyindirectly measurable breakdown or disturbance values or straying in thelight of directly measurable deviations and system condition values 12are ascertained in the second adaption loop 11.

[0251] A correction and/or compensation for such breakdown influences iscarried out either by changing the parameters which influence thebreakdown values and/or in that the breakdown values are reconstructedby virtual breakdown values and are compensated for on the basis of suchvirtual breakdown values.

[0252] In both instances, the breakdown value is corrected orcompensated for so that the breakdown influences or the breakdown valuesare eliminated or reduced to a permissible level. By copying thebreakdown values with virtual breakdown values, the actual cause of abreakdown cannot be localized conclusively; however, the influence ofthe breakdown value upon the overall system can be positively influencedin the above sense.

[0253]FIG. 3 further shows a block circuit diagram of a torque systemregulation with adaption and its cooperation with a selected path andsetting member. The torque regulation to be described hereinafter can beused for systems, such as torque transmission systems, with or withoutload distribution or branching off.

[0254] Compensation or adaption for the secondary consumers takes placein the adaption block 7. The secondary assemblies, such as, e.g., adynamo, a steering wheel pump or a climate control, establish one branchof the torque- and/or output flow in that a part of the input torqueM_(mot) supplied by the engine is taken up by the correspondingaggregate. For a clutch regulation, this means that one proceeds from aninput torque M_(mot) which is not actually available, i.e., that thedesired clutch torque derived from the supposedly higher engine torque,and hence also the thus detected correcting variable or setting value,are excessive.

[0255] The detection of such load distribution which, hereinafter, willbe designated, as adaption of the secondary consumers, can occur forexample by evaluating corresponding additional signals denoting measuredvalues, such as the switching on or switching off of the climate controlcompressor, climate control unit and other secondary consumers.

[0256] Correction for interferences which can be caused by measurablevalues, such as for example temperatures (e.g., the cooling watertemperature has an effect upon the engine torque) or RPM or the frictioncoefficient can be changed due to slip, is carried out in a secondadaption loop 9. Hereinafter, such corrections will be designated as“adaption 1”. In this case, a correction and/or compensation can takeplace either through parameter adaption, e.g., a correction of thefriction value, in the further compensation block 28 or in the transferblock 30 as a function of temperature or by a system adaption in theform of theoretically or empirically established disturbance orbreakdown models or patterns, e.g., a non-linear correction of theengine torque as a function of temperature.

[0257] In the third adaption block 11, interferences—which can be causedthrough non-measurable system input values and/or aging and/orstraying—are corrected and/or compensated for. Since this class ofdisturbances, such as e.g., aging or straying, cannot be detected on thebasis of measurable input values, it must be detected by observingsystem reactions. This means that such disturbances cannot becompensated for by preventive undertakings prior to actually takingeffect; instead, the reaction of the system as a deviation from theexpected behavior must be observed to be thereafter corrected and/orcompensated for.

[0258] These deviations can either be measured directly, e.g., by meansof a torque sensor at the clutch or, alternatively, they can becalculated from other measured values by resorting to a method model orpattern. In the event of detection, it is necessary to obtaincorresponding characteristic reference fields or unequivocal referencevalues of the system. In order to compensate for a thus detecteddisturbance or breakdown, it is necessary either to thereupon localize(single out) and correct the source of the breakdown or, alternatively,one assumes for example the existence of a virtual breakdown source A orB at which the detected deviation is corrected. In the same way, adisturbance or breakdown can be attributed to an existing block, such asfor example the engine block 13 or the inverse transmission function ofthe transmission unit in the transmission block 30.

[0259] The ascribing of the disturbance can be fictitious, i.e., such ablock is not actually responsible for the disturbance. Therefore, and incontrast with the regulation, the detection of the condition values orparameters need not be carried out permanently and can be limited tocertain operating ranges.

[0260] In those phases where no adaption takes place, one utilizes theadapted parameters which were detected during an earlier adaption phase.

[0261] As shown in FIG. 3, the input torque 15 M_(mot) supplied by thedriving assembly 16, such as for example an internal combustion engine,is formed and/or calculated in the characteristic engine block 13 from avariety of input values 14.

[0262] The values which are used to this end comprise at least two ofthe following values, namely the RPM of the driving aggregate, the loadlever position or the accelerator pedal position denoting the rate offuel delivery, the subatmospheric pressure in the suction intakemanifold, the injection time, the fuel consumption, etc. Furthermore,when forming or calculating the input torque M_(mot) 15, it is possibleto process the information already obtained and relating to possiblebreakdown influences (wear, temperature).

[0263] In the interlinking block 17, there is established aninterlinking which effects a correction of the driving torque by takinginto account the secondary consumers in the adaption block 7. Suchcorrection is carried out additively in such a way that the branched offtorques of the secondary consumers detected in 7 are subtracted from theengine torque 15 M_(mot). Hereinafter, this corrected engine torque willbe referred to as M_(Netto) 18. The engine torque which is corrected bythe branched off torques of the secondary consumers constitutes theinput value for the block 19 which serves as a compensation block forthe breakdown value correction or comparison. By resorting tocorresponding correction factors or corrective undertakings, thecompensation block 19 renders it possible to simulate breakdown sourceswhose breakdown values are or can be comparable to the actuallyoccurring breakdown values. The virtual breakdown values are returned tothe adaption block 9 and constitute the balance of the differencebetween (a) the deviations and/or fluctuations which occur in the systemas a result of for example manufacturing tolerances, contamination, etc.and (b) the desired conditions.

[0264] The correction can be carried out through additive,multiplicative, functional and/or non-linear proportions. In general, itis of importance to compensate for or to reduce the effect of thedisturbances to an acceptable level within a range of acceptable limitvalues. For example, additive disturbances or breakdowns can be takeninto consideration in the form of a virtual consumer and thussuperimposed upon the driving torque even if the disturbance orbreakdown has a different physical cause.

[0265] In a dynamic block 20, the dynamics of the method to beregulated, e.g., in the form of taking into consideration the massmoments of inertia (for example, of the moving mass of the engine) canbe subjected to follow-up control if this is advantageous for thebehavior of the system or for the control. For example, this enhancesthe quality of the regulation in the event of pronounced accelerationsor delays. Hereinafter, the thus dynamically corrected driving torque 21will also be designated as M_(AN).

[0266] In an operating point detection block 22, the desired clutchtorque M_(KSoll) is established in dependency upon the then prevailingoperating point. This is calculated from a percentual share of thedynamically corrected torque MAN and a safety torque M_(Sicher) which isdescribed in a safety block 25. The percentual share is determined in afurther characteristic field block 23 by the torque division factorK_(ME). The percentual share of the dynamically corrected torque can bealtered by a further correction block 24.

[0267] In systems with a genuine load distribution or branching off,such as in the case of a converter with a lockup clutch, the proportionof the safety function can become M_(Sicher)=0 since a torque is builtup by way of the converter in the event of slip.

[0268] In the case of an overall system without load distribution, thesafety function M_(Sicher) must ensure that, for example, in the eventof slip, an additive torque is added to the existing torque to thusprevent the buildup of an excessive slip value.

[0269] The correct proportion factor K_(ME) for each operating point isfixed or ascertained in the characteristic field block 23. This factorK_(ME) is memorized or stored in the corresponding characteristic fieldsor characteristic lines in which one or more of several values includingthe engine RPM, the engine torque, the driving speed, etc. are entered.This K_(ME) factor represents, in the case of two systems with a loaddistribution in the manner of a converter with lockup clutch, the ratioto be set by the control between the transmissible clutch torque and theavailable shaft torque.

[0270] In systems without load distribution, the direct proportion ofthe torque regulation is fixed by the proportion factor K_(ME). Theremaining torque is transmitted in the form of slip-dependent safetytorque which is ascertained in the safety block 25.

[0271] A further dynamic correction and/or compensation for thepreviously detected percentual share of the torque can take place in thecorrection block 24. This correction and/or compensation can be carriedout in such a way that one limits the rise of the desired torque and itwill hereinafter be referred to as “gradient restriction”.

[0272] For example, the gradient restriction can be carried out in theform of a maximum permissible increment per scanning step or through apredetermined modus operandi as a function of time. In view of suchundertaking, the activation of the power train is restricted to amaximum permissible value and a satisfactory and comfortable load changebehavior is thereby achieved.

[0273] A safety torque M_(Sicher) is determined in the safety block 25at each operating point. For example, such safety torque can becalculated in dependency upon the slip RPM. In this case, the safetytorque would become greater in response to increasing slip. In thismanner, one can protect the clutch in systems without load distribution.

[0274] Furthermore, a safety function of such kind renders it possibleto prevent or reduce thermal overloading of the transmission system. Thefunctional interdependence between the safety torque and the slip can bedescribed by a corresponding function or can be predetermined throughcharacteristic lines or characteristic fields. The output value, namelythe desired clutch torque, of a superposed block 26 can be expressed by

MK _(Soll) =K _(ME) M _(AN) +M _(Sicher)

[0275] wherein the correction block 24 is not considered in equation.

[0276] If the block 24 is taken into account, the desired clutch torquecan be described as

MK _(Soll) =d _(Dyn)(K _(ME) *M _(AN))+M_(Sicher)

[0277] wherein d_(Dyn) (K_(ME)*M_(AN)) contains the correction dynamicsor accounting for the dynamics in the block 24.

[0278] The desired clutch torque is determined through those values ofthe torque division factor K_(ME) and safety torque M_(Sicher) 25 whichare dependent upon the operating point detected at 22.

[0279] It is possible to again carry out a correction of the desiredclutch torque M_(KSoll) with a second virtual breakdown source B in thefurther compensation block 28.

[0280] Such corrected desired clutch torque M_(KSollkorr) 29 isconverted into a setting value in a transfer block 30 by an inversetransmission function of the transmission unit of the setting member 31.The transmission unit with the setting member 31 is controlled by meansof this setting value so that the transmission unit then carries out thecorresponding operations.

[0281] The transfer unit with setting member indicated at 31 is intendedto embrace, inter alia, systems with load distribution such as torqueconverters with lockup clutches or systems without load distribution inthe form of a clutch, such as for example friction clutches. Forexample, clutches which are used in systems without load distributioncan be wet clutches, dry clutches, magnetic powder clutches, turning setclutches, safety clutches, etc.

[0282] The generation of the energy/force required to operate thesetting member 31 can take place, for example, electromotorically,hydraulically, electrohydraulically, mechanically, pneumatically or inanother way.

[0283]FIG. 4 is a block circuit diagram of a control method withadaption and shows the overlapping control block 5 as well as individualadaption blocks. The block 4 of the control path (not shown in thisFigure) with setting member of FIG. 3 is equally valid for the FIG. 4and can be taken over from FIG. 3.

[0284] Starting from the characteristic field block 13, one shouldassume the presence of an engine torque 15 which is processed additivelywith a correction torque 42 in such a way that the correction torque 42is subtracted from the engine torque 15. The torque differential 43 islikewise additively corrected by the branched off torques of thesecondary consumers 7 and, here again, the torques of all relevantsecondary aggregates are subtracted from the torque differential 43 inaccordance with their condition.

[0285] The thus treated moments or torques of the secondary consumers orsecondary aggregates are ascertained or calculated from data or signalsof the operating point 22 of the individual aggregates and/or fromadditional signals 44, such as for example switch on and/or changeoverand/or switch off signals or typical operational signals, such as forexample current-voltage signals of the dynamo.

[0286] For example, the detection can be carried out in that typicaloperational signals are stored in a characteristic field or acharacteristic line and thus an associated torque requirement of thesecondary consumers is determined by reading a characteristic field or acharacteristic line. An equally possible alternative mode of detectionis to store equations or equation systems where the signal values areentered as parameters and the solving of such equations or equationsystems determines the torque requirements.

[0287] The corrected signal can undergo a dynamic correction independency upon the dynamic block 20. For example, the dynamic block 20takes into consideration the moments of inertia of the rotarycomponents, such as engine parts and for example the flywheel, or themoments of inertia of other components of the power train. The operatingpoint 22 is ascertained or calculated from the condition values 40 ofthe system. This can be made possible by ascertaining data fromcharacteristic fields or by solving the equations or equation systems,the condition values being introduced into such equations as parameters.

[0288] For example, the torque division factor K_(ME) 23 is ascertainedfrom a characteristic field at the operating point 22. A dynamicallycorrected signal 46 is multiplied by the torque division factor 23 tothus determine the torque which is transmitted, for example, by aconverter lockup clutch of a hydrodynamic torque converter withconverter lockup clutch. Again, the signal can be corrected withassistance from the dynamic block 24.

[0289] In the example which is shown in FIG. 4, the dynamic block 24 isrealized as a gradient restriction, i.e., a restriction of the maximumrise of the torque. Thus, this gradient restriction can be realized insuch a way that the rise of the torque is compared, as a function oftime within a fixed interval of time, with a maximum permissible value,such as for example a ramp and, when the actual rise exceeds the maximumvalue of the ramp, the ramp signal is used as the real value.

[0290] A further possibility of limiting the gradient can be achievedwith a dynamic filter. The time behavior of the filter as a function oftime can be selected in a number of ways depending upon the operatingpoint so that, when using for example a PT₁ filter, the time constantcan be set as a function of the operating point.

[0291] As shown in FIG. 4, an output signal 47 of the block 24, namelythe desired clutch torque M_(KSoll), to the transfer unit is transmittedto the transfer unit with setting member. Such desired clutch torque iscompared with the actual clutch torque MKIST 48 at a junction 49. Suchcomparison is ensured by an additive method according to which theactual clutch torque 48 is subtracted from the desired clutch torque 47to thus arrive at a difference ΔM 50. The torque difference ΔM isprocessed in the next-following blocks 51, 53, 54 of the block circuitdiagram into the correction torque 42 which is processed with the enginetorque 15 at the junction 52.

[0292] The adaption of, in this example, FIG. 4 does not carry out anylocalization of the breakdown values but traces the disturbances tofictitious breakdown values or disturbances. The correction of and/orthe compensation for real breakdown values by means of fictitionalbreakdown values no longer requires a localization and, accordingly, nolonger the correction of real causes of defects and errors. In theexample of FIG. 4, the engine torque or characteristic field of theengine is regarded as the fictional breakdown source so that alldeveloping errors and disturbances are regarded as disturbances of theengine torque and are compensated for or corrected by an enginecorrection torque M_(mot) _(—) _(korr).

[0293] The purpose of the adaption is to realize the most accurateachievable setting of the torque division factor K_(ME) as regards thequality of reaction to disturbances and optimizing of the physicalbehavior of the system.

[0294] The correction value M_(mot) _(—) _(korr) can be ascertained bysolving the equations or equation systems and/or by using acharacteristic correction field. The characteristic correction field canbe arrived at in such a way that the correction value is recorded forexample over two parameters. When determining the characteristiccorrection field, it is possible for example to use the same parametersthrough which the characteristic engine field is recorded, such as forexample the fuel consumption and the engine RPM. However, it is alsopossible to use as one parameter of this characteristic correction fielda value which reflects a dependency of the transfer function upon thepath, such as for example the turbine RPM.

[0295] The design of such a characteristic correction field over theengine torque and the engine RPM can be effected for example by fixingthree supporting points. By resorting to three supporting points, it ispossible to fix a plane which determines the characteristic correctionfield as a function of the two dimensions or parameters. A furtherpossibility consists in the selection of four supporting points todefine a surface which determines the characteristic correction field.In this context, a block 51 carries out a weighting or evaluation of thesupporting points as a function of the respective operating point. Thisweighting of the supporting points is carried out since an indicationconcerning the correction values as at other operating points can bemade over the surface of the characteristic correction field from eachoperating point. However, since this can result in errors, and theindications in partial areas of the characteristic correction fieldcannot be linearly transferred into other partial areas, one introducesthe weighting of the supporting points.

[0296] The consequence of such weighting is that, depending upon thecorresponding operating point or the region of the operating point, thesupporting points are weighted differently and thus the influence ofpoints in the characteristic correction field which are more distantfrom the operating point has a lesser or greater significance. Theweighting of the supporting points takes place in a block 53 whichinfluences the time behavior of the adaption. A block 54 constitutes acharacteristic correction field block which determines, on the basis ofthe operating point 22, the correction value 42 of the engine torque andsuch correction value is processed with the engine torque 15 at thejunction 52.

[0297]FIGS. 5a to 5 c show diagrammatically the possible disturbances ofthe engine torque as a function of time. FIG. 5a shows the desiredtorque as a horizontal line, and the actual torque is shown as ahorizontal line with a step. This step can be identified as an additiveportion of the engine torque which, for example, is caused by additionalaggregates. For example, a step in the actual torque develops when anadditional aggregate is turned on, into or off a particular operatingcondition. Depending upon whether the branched off load is increased orreduced, the step can increase or lower the actual torque. Based on theheight of the step and its behavior as a function of time, it ispossible to obtain an indication as to which additional aggregate wasturned on, off or over.

[0298]FIG. 5b shows the desired torque and the actual torque at anoperating state different from that represented in FIG. 5a. Thedifference between the two curves can be designated as a breakdown valuewhich influences a multiplicative share of the clutch torque. Thus, acompensation and/or correction of such breakdown value must exhibit amultiplicative characteristic.

[0299]FIG. 5c again shows the desired and actual torques but the twotorques are separated from each other by an additive portion. Thecorrection and/or compensation for such disturbance can be undertakenthrough an additive portion of the clutch torque. For example, theexample of FIG. 5b can be explained as a result of a change of thefriction value and the example of FIG. 5c can be explained as beingbased upon a deviation of the setting value.

[0300]FIG. 6 illustrates a characteristic correction field wherein theengine correction torque is represented as a function of the enginetorque and the engine RPM. The four corner points of the value range areused primarily as supporting points 55. The weighting of the supportingpoints 55 in the block 51 of FIG. 4 can be carried out, for example, inthat at a certain operating point the vertical positions or levels ofthe supporting points are changed so that the area closely surroundingthe operating point undergoes a greater weighting. Such weighting as aresult of a change of the vertical positions of the supporting pointscan be designed, depending upon the operating point, in such a way thatthe change is experienced by one to four supporting points.

[0301] The fixing of the four supporting points 55 which define asurface can also be modified in that one starts with six supportingpoints 55 (see FIG. 6a) with three supporting points always arrangedalong an axis and the six supporting points define two surfaces eachwith four supporting points, two supporting points being common to twosurfaces.

[0302] A further embodiment can be characterized in that one employsnine supporting points (see FIG. 6b) in order to define four surfaces.The characteristic field is set up in such a way that the points of eachpair of neighboring supporting points belonging to a common surface areconnected with one another by a straight line so that the definitionrange of such surface is bounded by four straight lines and theprojection of the characteristic field onto the definition rangeconstitutes a polygon, as a rule not a rectangle or a square. Theconnecting lines between two opposing straight boundary lines of thecharacteristic field which lie in a common plane spanned by a straightmarginal line of the characteristic field and the axis of the definitionarea of the characteristic field likewise constitute sections ofstraight lines.

[0303] A further embodiment of the characteristic field of FIG. 6 canrepresent a curved surface which is generated in a three-dimensionalspace according to a functional connection, such as for example aparabola of the second order. The surface which characterizes thecharacteristic field can be a curved surface which is defined by certainsupporting points and/or by a functional connection or an equation orequation system.

[0304]FIG. 7 shows a block circuit diagram resp. a flow or developmentdiagram of a torque regulation with adaption of a torque transmissionsystem which will be explained in greater detail below. For example, thetorque transmission system can be a clutch, such as a friction clutchand/or a starting clutch of an automatic gearbox and/or a transfer meansof an infinitely adjustable cone pulley belt contact gearbox and/or ahydrodynamic torque converter with a converter lockup clutch and/or aturning set clutch and/or a safety clutch. The actuation of the torquetransmitting parts can be carried out by way of an electromechanical, anelectrohydraulic and/or a mechatronic and/or a mechanical and/or ahydraulic and/or a pneumatic setting member.

[0305] As shown in FIG. 7, the driving torque 62 of a driving aggregate61, especially an internal combustion engine, is first calculated fromdifferent input values 60. The values used here comprise at least two ofthe following values, namely the RPM of the driving aggregate, the loadlever position or accelerator pedal position of the fuel supply,subatmospheric pressure in the suction intake manifold, injection time,consumption, etc. As already stated above, the driving aggregate isdenoted by the block 61 and the input torque of the driving aggregate isindicated at 62. The block 63 represents a junction which effects acorrection of the input torque. Such correction is carried out by meansof correction factors which are supplied by the system adaption 64. Thissystem adaption 64 can constitute a program module which, based onadditional input values 65, on analytically or numerically determinedvalues, and on values of characteristic line fields, carries out acorrection of the average input torque. These correction factors cancompensate for deviations from a desired state which deviations developin the system, namely by compensating for such deviations by additive,multiplicative and/or nonlinear shares.

[0306] A block 66 represents the determination or selection orcalculation of a torque division factor K_(ME) which is correct for eachexisting operating condition and which (as a rule) is between 0 and 2.However, system conditions can also occur which render it necessary touse a larger K_(ME) factor. This K_(ME) factor denotes the torque ratioM_(Kupplung) to M_(Antrieb-korrigiert) to be set by the controls as oneof the values fixed in advance for each operating point in the manner ofa characteristic field from the relevant selected weighting of thecriteria indicated in FIG. 2, i.e., the K_(ME) factor is memorized in acharacteristic field for the individual operating conditions.

[0307] However, the K_(ME) factor can also be considered to be constantwithin the entire operating range. Fixing or calculation of the K_(ME)factor can also be undertaken through an equation or through an equationsystem whereby the solution of the equation or equation systemdetermines the K_(ME) factor.

[0308] Condition values or parameters of the vehicle and the design oftorsion dampers which may be present can be realized or considered inthe characteristic field of the K_(ME) factor or in the analyticalequations for determining the K_(ME) factor. The design of the damper ordampers, if used, for example in a lockup clutch, is of particularimportance since if a damper is present, the K_(ME) factor can be keptconstant at least within a comparatively large section of the operatingrange of the internal combustion engine or of the hydrodynamic torqueconverter.

[0309] A K_(ME) factor which is kept constant within a wide operatingrange can also be arrived at for clutches, such as friction clutches orstarting clutches.

[0310] The ratio of clutch torque to input torque is fixed by the torquedivision factor K_(ME). This renders it possible to operate, forexample, with torque-controlled slip. In systems having a loaddistribution (e.g., in converters with lockup clutches), that share ofthe torque which is to be transmitted by the lockup clutch is fixed bysuch factor. In systems without load distribution, e.g., in clutchsystems, not less than 100% of the torque existing at the input side canbe transmitted in a stationary operation. In such instances, the factordetermines that proportion which is directly transmitted by the torquecontrol. The remaining share of the torque is controlled by follow upthrough a slip-dependent safety torque which copies a converter-likebehavior. The calculation of the desired clutch torque is carried out at67 by means of the then existing KME factor, and the corrected inputtorque of the driving aggregate. A further correction of the desiredclutch torque can be carried out at a junction 68 by additive,multiplicative and/or non-linear shares resulting from the systemadaption 64. Thus, it is possible to provide the junction 68. In thismanner, one arrives at a corrected desired clutch torque. it issufficient, for many applications, if only one of the two junctions 63,68 is provided; it is preferred to retain the junction 63.

[0311] The calculation of the setting value is carried out at 69 on thebasis of the corrected desired clutch torque of the inverse transferfunction of the path which represents the lockup clutch or the clutch. Ablock 70 represents the inverse transfer function of the setting memberwhich is resorted to in order to calculate the setting value which isrequired for a setting member 71. The setting value thus influences acontrol path 72 which, in turn, influences the vehicle 73. The valueselected by a setting member can be reintroduced into the control devicein order to enhance the quality of the control method. For example, thiscan relate to the position of the master cylinder of a hydraulic systemset by the electric motor of an electrohydraulic setting member. Suchreintroduction takes place in two blocks 74 and 75. A further block 76denotes a calculator unit which serves to simulate a model of thevehicle and of the torque transmission system.

[0312] A block 77 denotes the transmission of those measured values orparameters of the vehicle which are processed as input values at anotherlocation, namely in a block 78.

[0313] The broken line denotes in FIG. 7 the transition area between acentral computer or control unit and the vehicle. The regulator outputvalue can be calculated at 70, and such value is formed on the basis ofthe setting value ascertained at 69 and the inverse transfer function ofthe setting member. The setting member preferably constitutes anelectrohydraulic or electromechanic setting member. It is advantageousto use a proportional valve or a pulse width modulated valve.

[0314] A feedback of the setting value can take place at 75 in the formof a regulation or adaption. However, such feedback can be dispensedwith. A measurement of the actual clutch torque can be carried out at79, e.g., through a torque sensor or through an expansion type measuringstrip (DMS).

[0315] In lieu of measuring the actual clutch torque at 79, it is alsopossible to carry out a calculation of such torque on the basis of thecondition values and the vehicle and converter physics. For example, tothis end the characteristic field of the engine and/or thecharacteristic field of the converter or values representing such fieldscan be processed in a processor or in a central processor unit and/orthey can also be stored in a memory. Furthermore, it is also possible tomemorize for this purpose a characteristic field (or a valuerepresenting such field) denoting the torque transmitting capacity of,e.g., a converter lockup clutch.

[0316] If a determination of the actual clutch torque is carried out at79 as well as at 76, it is possible to balance the measured actualclutch torque with the actual clutch torque which was calculated byresorting to a model. The balancing can take place as a logicalinterlinking, e.g., on the basis of the minimum-maximum principle or asa probability comparison. The system adaption which is shown at 64 inFIG. 7 can be utilized to carry out, inter alia, the followingcomparisons and to complete the corresponding corrections:

[0317] A: Comparison of the corrected desired clutch torque with theactual clutch torque. Such comparison can also be made a long-termcomparison, e.g., by observing the deviation through a simultaneouslymoving time window. One can make a comparison between the correcteddriving torque and the backwardly calculated driving torque, and suchcomparison can also be carried out long-term, e.g., by observing thedeviations through a simultaneously moving time window. Likewise, it ispossible to carry out an evaluation of additional signals, such as forexample switching on or off of additional aggregates, for example, theclimate control, the compressor, the gear shift, etc.

[0318] B: Detection of the system deviation determined at A intoadditive, multiplicative and/or non-linear shares of M_(Antrieb) andM_(Kupplung) and the resulting division into the corresponding adaptionloops 80 and 81 or into the junctions 63 and 68.

[0319] The detection or determination of the corresponding shares ofM_(Antrieb) and M_(Kupplung) can be carried out, for example, accordingto the three diagrams of FIGS. 5a to 5 c.

[0320]FIG. 7 shows a development diagram of the control method with theindividual process steps. In a first process step, a driving torque ofthe engine is determined on the basis of a plurality of input values.There follows a first correction of this value according to theprorating by a system adaption. This system adaption is a program modulewhich carries out a correction of the average driving torque on thebasis of additional input values, analytically determined values andcharacteristic line fields. In a further process step, such correcteddriving torque is multiplied with a proportion factor K_(ME) which canbe between zero and two. Such proportion factor K is memorized in acharacteristic field for the individual operating conditions. Thischaracteristic field can store parameters or condition values of thevehicle and the design of the torsion damper or dampers, if any. Theratio of clutch torque and driving torque is fixed by the proportionfactor K_(ME). In this manner, it is possible to achieve an operationwith controlled slip.

[0321] In systems with load distribution (converter with lockup clutch),such factor determines that percentage of the torque which is to betransmitted by the lockup clutch. In systems without load distribution(clutch system without a parallel-connected converter), not less than100% of the torque existing at the input side can be transmitted in astationary operation. In this case, the factor fixes that part of thetorque which is directly transmitted through the torque control. Theremaining part of the torque is controlled afterwards through aslip-dependent safety torque which copies a converter-like behavior.

[0322] The achieved desired clutch torque is corrected again in a nextprocess step on the basis of system adaption. In this manner, onearrives at a corrected desired clutch torque. In the last step, asetting value is ascertained from such corrected desired clutch torquewith assistance from an inverse transfer function of the control path.By using the inverse transfer function for the setting member, the valueappearing at the output of the control device is obtained from suchsetting value. The thus obtained output value is transmitted to thesetting member which, in turn, acts upon the control path and thevehicle. The value set by the setting member can be retransmitted to thecontrol device to improve the quality of the regulating method. Forexample, this can involve the position of the master cylinder asselected by the electric motor. Furthermore, additional system values,such as for example the clutch path, or vehicle values, can betransmitted to the control device. These additional input values arethen introduced into the described regulating or control method throughsystem adaption.

[0323]FIG. 8 shows a simple model of an adaption which is limited toadditive correction of the input torque. The deviations which resultfrom the difference between the desired and actual clutch torques areadapted through virtual breakdown sources. The block 61 of FIG. 8denotes the driving aggregate, such as an internal combustion engine,which generates an engine torque 62. A block 90 represents the adaptionby means of virtual breakdown sources, and its output signal isprocessed additively with the engine torque 62 at a junction 91. Thecorrected engine torque is corrected dynamically in the block 2 by meansof dynamic correction based upon moments of inertia of the flywheel.

[0324] The torque arising for example at the torque converter withlockup clutch is divided into two parts by the torque division factor.One part is transmitted by the lockup clutch 3 b, and the differentialbetween the existing torque and the torque transmitted by the lockupclutch is transmitted by the torque converter 3 a.

[0325]FIG. 9 shows a block or flow diagram of a control method fortorque transmission systems. The broken line in the lower half of FIG. 9represents the separation between the central computer unit and thevehicle. The regulating or control method of the block circuit diagramshown in FIG. 9 represents a simplified adaption. The lockup clutch isstarted electrohydraulically through a proportional valve or a pulsewidth modulated valve. The output signal of the regulating computer orthe computer output value is a setting current which is set inproportion to a scanning ratio being applied, for example, at a pulsewidth modulated output of the computer. For example, the clutch torqueresults from the pressure differential applied in this way to theconverter lockup clutch or between the two plenum chambers of the lockupclutch. The system adaption is restricted to the adaptive correction ofthe input torque whose deviation results from the difference between thedesired and actual torques.

[0326] In comparison with FIG. 7, the embodiment of the control orregulating method according to FIG. 9 omits the junction 68 or thereturn transmission of the corrected input torque (M_(ANkorr)) In FIG.9, the desired pressure differential DP_(Soll) is determined at 100,namely as the main value in dependency upon the desired clutch torqueand, where applicable, also in dependency upon the corrected inputtorque MANkorr and the turbine RPM N-turbine as parameters.

[0327] An additional function block 101, corresponding to the block 70of FIG. 7, is divided into two subfunction blocks 101 a and 101 b.Feedback couplings 102 a and 102 b are provided for the respectivefunction blocks 101 a and 101 b. The input value of the inverse transferfunction of the setting member (101=101 a and 101 b) is the desiredpressure differential (DP_(Soll)) which is calculated in the block 100.The output value is obtained through the associated scanning ratio andconstitutes the regulator output value.

[0328] The setting member, which follows, is divided into an electricalsetting member portion which is formed by an end phase and the valvewinding, as well as into the hydraulic setting member portion which isrelevant for the corresponding pressure application at the converterlockup clutch, see the block 103. The input value of the electricalsetting member portion is the scanning ratio. This is converted at theoutput side into an actual current. Depending upon this actual current(I-Ist), the hydraulic setting member portion selects a correspondingpressure application to the converter lockup clutch. This takes place byselecting a corresponding pressure differential between the chambers ofthe converter lockup clutch.

[0329] The block 101 a denotes the inverse function of the hydraulicsetting member portion in that the corresponding desired current iscalculated from the desired pressure. Such portion of the setting memberincludes a feedback of the measured actual pressure in the form of apressure adaption which is denoted by the block 102 a. This pressureadaption 102 a supplies the corrected desired current. The second part101 b of the inverse transfer function 101 of the setting memberconstitutes the electrical portion which calculates the correspondingscanning ratio from the corrected desired current. A PID regulatingalgorithm is used to this end. The input value I_(Soll-R) for theinverse transfer behavior of the electrical setting member portion iscalculated with the PID regulator from the control deviationI_(Soll-Korr)=⁻I_(Ist) (I_(Ist) is measured past the valve winding).

[0330] The numbering of individual blocks which is selected in FIG. 9corresponds essentially to the numbering of the individual blocks inFIG. 7. In this way, the individual function blocks of the specialelectrohydraulic embodiment shown in FIG. 9 can be related to those ofthe generic design according to FIG. 7.

[0331] The individual reference characters shown in FIG. 9 denote thefollowing:

[0332] DP_(Soll)=110=desired pressure differential at the lockup orconverter lockup clutch. It corresponds to the differential between thepressures prevailing in the chambers at opposite sides of the piston ofthe lockup clutch.

[0333] DP_(Ist) 111=actual pressure differential between the twochambers of the converter lockup clutch.

[0334] P_(Nach)=, pressure downstream of the lockup or converter lockupclutch.

[0335] I_(Soll)=113=desired current for the electrohydraulic valve.

[0336] Δ114=RPM differential between the pump and the turbine of theconverter; thus, ΔN=N pump−N turbine.

[0337] The parameters of the vehicle 115 indicated in FIG. 9 in front ofthe block 76 are indicative of the slip in the lockup clutch or in theconverter.

[0338] As can be seen in FIG. 9, the RPM differential ΔN=N pump−Nturbine does not represent any regulating value as is the case inconnection with conventional slip regulations. In accordance with thenovel torque regulation or control, this RPM differential ΔN is used asa condition value of the path to be controlled to monitor possibletorque deviations which, in turn, have a correcting backlash effect uponthe regulation in the adaption through corresponding junctions. Theascertained torque values can be stored, e.g., in the manner of asimultaneously moving time window, for a certain period of time in orderto detect the proportions of deviations at the clutch and at the engine.This takes place in a system adaption shown at 116.

[0339] The control or regulation according to the invention exhibits theadditional advantage that the adaption of the breakdown proportions ofthe driving torque can also take place with the lockup or converterlockup clutch fully disengaged, i.e., with K_(ME)=0. To this end, thenominal driving torque is compared with the torque acting upon theconverter; this takes place at the junction 63 shown in FIG. 7 or at theprocess step of FIGS. 7 and 9. Through this adaption, and inanticipation of a later engagement of the lockup clutch, possibledeviations of driving torque are considered already in the disengagedcondition of the lockup clutch. To this end, the torque being applied tothe converter is determined in the system adaption 116 or 64.Preferably, the converter characteristic field is stored or memorized inthis system adaption for such purpose. By determining the RPMdifferential between the turbine and the pump of the converter, it isthus possible to determine the applied torque. Such converter torque isthen compared with the nominal input torque of the engine or drivingaggregate. This input torque can be derived from a stationarycharacteristic field of the engine which is memorized in the block 61 ofFIGS. 7 and 9, namely as a result of the measured condition values suchas especially the engine RPM, load lever position, fuel consumption,injection amount or injection time, etc. The RPM differential betweenthe turbine and the pump of the torque converter can be determined inthe block 76.

[0340] Furthermore, it is possible to determine the converter torquealready in the block 76; the converter characteristic field is thenmemorized in the block 76.

[0341]FIG. 10 shows a vehicle 201 with a combustion engine 202 whichacts upon a gearbox 204 through a clutch 203 which is self adjusting orcompensates for wear. The gearbox 204 is connected, through a driveshaft 205, with a driving axle 206 of the vehicle 201. With the selfadjusting clutch 203 or with a clutch which compensates for wear, onedistinguishes between an input side 207 which is adjacent the combustionengine 202 and an output side 208 facing the gearbox 204. The engagingand disengaging system for the clutch 203 is connected with a slavecylinder 210 which is connected with a master cylinder 211 through ahydraulic conduit 209. A clutch engaging and disengaging system, such asa mechanical disengaging bearing, can come into contact with the tonguesor prongs of the diaphragm spring in such a way that it determines thebias of the diaphragm spring upon the pressure plate in a directiontoward the engine and thus the bias upon the friction linings betweenthe pressure plate and the flywheel. The hydraulic conduit 209 isconnected, by the master cylinder 211, with an electric motor 212 whichis confined in a housing together with the master cylinder 211 toconstitute therewith a setting member 213. A clutch movement detector214 is mounted in the same housing immediately adjacent the mastercylinder 211. Furthermore, a control apparatus (not shown in thedrawings) is mounted on a circuit board 227 (FIG. 11b) in the settingmember housing. This electronic control device contains the output andalso the control electronics and is thus mounted entirely within thehousing of the setting member 213.

[0342] The control apparatus is connected to a throttle valve sensor 215which is mounted directly on the combustion engine 202, with an engineRPM sensor 216, and with a tacho sensor 217 which is mounted on thedriving axle 206. Furthermore, the vehicle 201 comprises a gear shiftlever 218 which acts upon the gearbox 204 through a switching linkage. Aswitching path sensor 219 is provided on the gear shift lever 218 and islikewise in signal transmitting connection with the control apparatus.

[0343] The control apparatus provides the electric motor 212 with asetting value in dependency upon the attached sensor system (214, 215,216, 217, 219). To this end, a control program is implemented in thecontrol apparatus, either as hardware or as software.

[0344] The electric motor 212 acts upon the self adjusting clutch 203through the hydraulic system (209, 210, 211) in dependency upon thesignals from the control apparatus. The mode of operation of clutchescorresponding to the clutch 203 is described in detail in publishedGerman patent applications Nos. 42 39 291, 43 06 505, 42 39 289 and 3222 677. The disclosures of these publications are referred to herein asforming part of the disclosure of the present application. An advantageof a self adjusting clutch 203 is that the forces which are necessary tooperate the clutch are considerably smaller than in conventionalclutches due to the wear compensating design of the self adjustingclutch. Thus, the electric motor 212 can be dimensioned to consume andtransmit smaller amounts of power and, therefore, the apparatus canemploy a more compact setting member 213. The setting member 213 of FIG.10 is not drawn to scale as compared with the other components of thevehicle 201.

[0345] The setting member 213 will be explained in greater detail withreference to FIGS. 11a, 11 b and 12 a, 12 b. The electric motor 212,preferably a direct-current motor, acts through an engine shaft 220 upona worm which meshes with a segment gear 222. The segment gear 222carries a pusher crank which is operatively connected with a piston 225of the master cylinder 211 by a piston rod 224. A snifting member 250with a snifting bore or hole 251 is provided on the master cylinder 211to compensate for thermal influences upon the hydraulic fluid.

[0346] The electric motor 212, such as a direct-current motor, exerts apull or push upon thepiston 225 of the hydraulic master cylinder 211through the gearbox which can be self locking. Such forces aretransmitted to the clutch 203 through the hydraulic conduit 209. In thismanner, the clutch 203 is engaged or disengaged in a controlled manner.

[0347] Since the parallel axes of the master cylinder 211 and the engineshaft 220 are located in different planes, i.e., they are offset, thesetting member 213 occupies even less room.

[0348] A servo spring 226 is provided in the piston 225 or within themaster cylinder housing 221 concentrically with the master cylinder 211.This servo spring 226 supports the electric motor 212 duringdisengagement of the clutch. The spring 226 is tensioned, in that itsbias is overcome, during engagement of the clutch.

[0349] The cooperation between the electric motor 212 and the spring 226will be explained with reference to the diagram of FIG. 13. The progressof forces is entered over the clutch movement. The solid line 237denotes the force which is supplied by the electric motor 212 duringengagement and disengagement of the clutch 203. The upper part of thisline denotes the force path during disengagement and the lower partduring engagement. Such progress of force indicates that thedisengagement necessitates the application of greater forces than theengagement. The dot-dash line 239 is the characteristic curve of theservo spring 226. The broken line 238 denotes the cooperation of forcesof the spring 226 and the electric motor 212.

[0350] The overall force 238 to be applied by the electric motor 212 isgreatly reduced, as shown by the displacement of the broken force line228 in the direction of smaller forces. Owing to the supporting actionof the properly selected servo spring 226, the characteristic curve ofthe electric motor or the diaphragm spring is shifted in the negativedirection and the maximum values observable in FIG. 13 in the positiveand in the negative directions of the broken line are approximatelyequal. Due to such supporting action of the servo spring 226, it ispossible to reduce the dimensions of the electric motor 212 incomparison with the dimensioning without the assistance from the servospring 226. The assistance by the servo spring in this way presupposesthat the electric motor is used in the pull and push directions.

[0351] In FIG. 12a, the servo spring 226 is mounted in the actor housingwherein it is installed between two abutments 227 a, 227 b. The abutment227 a is spring biased against a spring ring 228 which is connected tothe piston rod, and the abutment 227 b bears against a portion of theactor housing. The gearbox is protected against contamination by arubber membrane 229 which is adjacent the abutment 227 a. Furthermore,the housing is provided with an aeration or ventilation bore 230 whichallows drainage in the event of the escape of hydraulic fluid.

[0352] The carrying out of the control or regulation method which can beimplemented with the control apparatus to regulate the torque in thetorque transmission system, such as a friction clutch, is shown insimplified form in FIG. 14. The regulating method is stored as asoftware program, for example, in an eight-bit processor of the controlapparatus. This regulating method can be used for example, to controlthe operation of 212.

[0353] The input torque M_(Mot) of the engine 202 is ascertained withassistance from the throttle valve sensor 215 and the engine RPM sensor216, and is made available to the control program as an input value. Theengine RPM sensor 216 detects an engine RPM N1, and the tacho sensor 217registers an RPM of the driving axle 206; the additional input valuesare also transmitted to the control program. A gearbox input RPM N2 iscalculated based on the RPM of the driving axle 206. The differencebetween the rotational speeds N1, N2 is designated a slip RPM. The slipRPM is determined analytically within the control program and ismonitored in order to ascertain whether or not it exceeds a thresholdvalue of the slip. The rise of the slip beyond the threshold value isdetected as a slip phase S. Such slip phase S prevails until the actualslip decreases below the threshold value.

[0354] The clutch torque M_(K) is calculated by means of a correctionvalue M_(Korr) in accordance with the equation M_(K)=M_(mot)−M_(korr).

[0355] The correction value M_(korr) is a torque which is increasedincrementally with the computer cycle and is reduced during theintervals detected as slip phases S in accordance with the controlprogram. This method ensures that the clutch 203 is continuously closeto a slip limit R. The slip limit R is the instant when the engine RPMNl begins to exceed the gearbox input RPM N2. This happens exactly whenthe torque being applied at the input side is greater than the thentransmissible clutch torque. Such method is satisfactory also when theinput torque is not constant.

[0356] The characteristic line field which is illustrated in FIG. 15 isevaluated prior to transmission of the setting value to the settingmember, especially in a torque transmission system such as a frictionclutch.

[0357] The region of possible positioning of the setting member, i.e.,the range of transmissible clutch torque, is measured along theabscissa. This region is divided into partial zones 240 one of which ishighlighted by hatching. This highlighted area or zone 240 denotes thatclutch torque which can be transmitted between 100 and 140 Nm. As longas the transmissible clutch torque which has been calculated accordingto the regulating method of the invention is within this partial zone, apermissible value of 140 Nm is assigned to the setting member. Theprocedure is analogous within other partial zones 240.

[0358] In accordance with this method, the number of setting movementsof the setting member is further reduced. The setting movement, namelyfrom one plateau to another plateau, is limited to a certain magnitude.This design of the characteristic field regarding the setting movementcan be such that the number of blocks or zones 240 can vary independency upon the nature of application. In general, theseundertakings prolong the life expectancy and reduce the energyrequirements of the actuatorism of the torque transmission system.

[0359]FIGS. 15a to 15 e show a selection of setting member positions tobe assumed in accordance with the regulating method for a desired clutchtorque.

[0360] By automating the actuation of the clutch, it is necessary toprovide an actor to facilitate the conversion of control signals intodisengaging or engaging steps or movements of the clutch. An adaptivecontrol of the setting behavior of the actor can be carried out in sucha way that one achieves a torque matching or torque follow up. Thereliance upon torque matching is advantageous because it can ensure thatthe setting member not only carries out the engagement and disengagementduring gear shifting and starting but also sets the clutch contactpressure during each stage of the driving operation so that thetransmissible clutch torque always corresponds to a desired clutchtorque reflecting the driving conditions or the operating point, or acorresponding desired contact pressure or reduced contact pressure incomparison with the clutch torque can be established. This ensures that,during gear shifting, the setting device or setter need not move fromthe fully engaged position and through the entire setting range in orderto disengage the clutch since, as a result of torque matching or followup, the setting device already occupies a position which corresponds tothe actually selected torque plus a desired offset value. In thismanner, the demands upon the dynamic behavior of the system, especiallyof the actor, can be reduced to ensure a maximum adjustment speed since,as a rule, shorter adjustment distances must be covered.

[0361] A dynamic torque matching or follow up designed in the aboveoutlined manner renders it necessary that the actor and the electricmotor remain in operation during the entire period of operation ordriving time in order to be able to carry out a quasi instantaneousadjustment according to dynamic changes of the actual torque.

[0362] With a regulating or control method which ensures a continuoustorque matching, an electric motor must constantly copy for examplevariations of the transmissible torque. A possibility of using theelectric motor only when required can lead to a copying of the clutchtorque which is realized in stages or in a stepwise fashion.

[0363] The regulating or control method can ensure at all times that theclutch can transmit a desired clutch torque as determined at eachsuccessive interval of time. Copying of the clutch torque entails thatone can tolerate slight overpressures Δ_(m) within a certain scatterband. This, in turn, means that follow-up movements of and thus the loadupon the setting member can be reduced. The curve 241 of FIG. 15adenotes the calculated desired clutch torque wherein the function 242corresponds to the desired clutch torque plus a certain scatter band.The values of the scatter band of the function 242 are derived from thestep height ΔM and from the requirement that the selected clutch torquemay not exceed the calculated clutch torque as well as that a change ofthe selected clutch torque is carried out only if the change exceeds athreshold value.

[0364]FIG. 15b shows by way of example a mode of operation in accordancewith a control or regulating method wherein the desired clutch torque isadjusted above a threshold value 243. When the value of the desiredclutch torque is less than or equal to the threshold value, the selectedclutch torque assumes a value which can be the same as or different fromthe threshold value. By fixing the scatter band and a correspondingstarting up, a definite excessive contact pressure develops withincertain operating ranges which, however, leads to a timely shortenedaction of the setter and, hence, the load upon the setter is alsoreduced. The method according to FIG. 15b shows that a minimum clutchtorque is selected at low desired clutch torques and thus the settermovements which are associated with a stressing of the setting systemcan be reduced. For example, the minimum clutch torque 243 can bedependent upon the operating point, e.g. , upon the transmission ratio,the setting of the gearbox, the engine RPM, the position of theaccelerator pedal, or upon a brake signal. FIG. 15c shows a dependencyof the minimum clutch torque as a function of the operating point; thestepped curve 244 conforms to the dynamic behavior of the operatingpoint and the copied clutch torque 241 is adapted accordingly.

[0365] The method which is shown in FIG. 15d leads to a minimum clutchtorque which is dependent upon the operating point plus a behaviorcombined according to the method of stepwise matching in relation to ascatter band.

[0366]FIG. 15e indicates a behavior of the clutch torque as determinedby a minimum clutch torque 243 which, however, cannot be illustrated inareas with constant value because it is a function of the time. Thisminimum torque is caused to conform through a step function 245 and,when the desired clutch torque 241 exceeds the minimum clutch torque, aquasi instantaneous copying of the torque is carried out withoutundertaking an adaption in relation to a scatter band.

[0367]FIG. 16 shows the circuit diagram of a conventional H-circuit. Onedistinguishes between individual shift lanes 250 and a selection path251 for the selection of individual shift lanes 250. The path covered bythe gear lever 218 within the shift lanes 250 is designated as a shiftpath 252. The directions of movement along the shift path 252 and theselection path 251 are indicated in FIG. 16 by corresponding arrows.

[0368] The position of the shift lever 218 can be monitored by twopotentiometers, especially linear potentiometers. One of thepotentiometers monitors the shift path, and the other potentiometermonitors the selection path. In order to carry out the monitoringoperation which can likewise be implemented in the control apparatus,one monitors and evaluates the shift path and/or the selection path. Themode of practicing the monitoring method will be explained withreference to FIG. 17. In FIG. 17, the signal paths which are relevantfor the monitoring method are shown in the form of a diagram as afunction of the time t. The coordinate inscriptions correspond to anydesired subdivision of the monitored shift path 252 within a computer.More specifically, a gear lever signal 260 is plotted as a function oftime t and such signal is directly proportional to the monitored shiftpath 252.

[0369] The plotted path of the gear lever signal 260 corresponds to atypical gear shifting procedure. The gear lever 218 remains in itsposition approximately up to the time t denoted here as 8.3 seconds. Upto such time, the gear lever signal 260 exhibits only the vibrationswhich are typical of a driving operation. Such vibrations typicallydevelop in the torque transmission system and are additionally caused todevelop from the outside, for example, due to unevenness of the roadsurface. After elapse of the time interval of 8.3 seconds, the gearlever 218 is moved along the shift lane 250 so that the intensity of thegear lever signal 260 increases from an approximate value of 200increments to about 480 increments. This value remains constant for acertain interval of time and corresponds either to a holding still bythe user or to the interval of time which is required to complete theadvancement along a selection path 251. Finally, a gear is engaged. Thevalue of the gear lever signal 260 increases to about 580 increments andremains substantially constant for a certain period of time. Thiscorresponds to the time interval which is required for thesynchronization of the gearbox ratio to be engaged. The intensity of thegear lever signal then rises to a value which corresponds to the newlyselected and engaged gear ratio. In addition, the gear lever signal 260is subjected to a digital or analog filtering with an adjustable timedelay so that one obtains a linearized filter signal 261 following thegear lever signal 260. The filter signal 261 is acted upon by a constantvalue and by an offset signal which is a function of the input torque ofthe driving unit 202. The thus obtained sum signal is shown in thediagram of FIG. 17 as a comparison signal 262.

[0370] The switching intent detection is carried out in dependency uponthe monitoring of the time dependencies of the progresses of the gearlever signal 260 and the comparison signal 262. As soon as the path ofthe gear lever signal 260 crosses the path of the comparison signal 262,a switching intention counter is set to zero and the monitoring of thetime dependencies started. This point of time is shown in the diagram,as at t₁. The count of the switching intention counter thereuponprogresses in dependency upon a computer cycle toward a predeterminedmaximum point of the counting value. In this manner, one provides anaccurately determined control time interval during which the detectedswitching intent is verified. During such interval, the counter can bestopped and reset to zero at any time in response to the application ofcontrol signals. Such control signals can be transmitted by an attachedsystem of sensors. These sensors monitor further influence values, suchas the input torque, the attached load or the further progress ofmovement of the gear lever 218. As soon as this sensor system picks upmeasured values which contradict the detected switching intention, acontrol signal is transmitted to the switching intention counter. Inthis manner, the torque transmission system is protected by theaforedescribed monitoring method against faulty releases. A switchingintention signal is transmitted to the next following operating systemonly when the switching intention counter reaches the predeterminedcount prior to transmission thereto of a control signal.

[0371] The gear lever signal 260 and the filter signal 261 generatedthereby are again shown drawn to a different scale. In order to generatethe comparison signal 262, the intensity of the filter signal 261 isincreased by a constant value and by an offset signal which is dependentupon the input torque. The constant value must be sufficiently large toensure that the path of upon the input torque. The constant value mustbe sufficiently large to ensure that the path of the gear lever signal260 does not intersect the path of the comparison signal 262, withoutthe existence of a switching intention, as a result of typicaloperational vibrations of the gear lever 218 during operation of thevehicle lever signal 260 because this could lead to undesired releases.This must apply even if the input torque, for example, as a result of aninterruption of fuel admission, has become zero and thus the offsetsignal has become zero. The time point for the withdrawal of the drivingtorque is designated as t₂ (FIG. 18). Thereafter, the comparison signal262 corresponds to an intermediate comparison signal 263 which isobtained additionally only from the filter signal 261 and a constantvalue. In operation, the constant value preferably conforms to theelasticity of the gear shift linkage and thus to the potential extent ofvibration, such as the vibration amplitude of the gear lever.

[0372]FIG. 19 shows the progress of a gear lever signal 260 in thecourse of an extremely slow gear changing operation. When the gearshifting is carried out with such pronounced delay, there exists thedanger that the gear lever signal will not intersect the comparisonsignal. This would entail that the existing shift intention would not bereliably recognized. For this reason, the monitoring method isadditionally expanded by the illustrated monitoring of the gear leverchange, i.e., of a change of the gear lever path as a function of time.Thus, the change of the gear lever signal 260 is monitored in that thepath change ascertained in a time window in a predetermined zone outsideof the space which the non-operated gear lever occupies is checked toascertain whether the intensity of the signal has decreased below athreshold value. If the intensity of the gear lever signal has decreasedbelow such threshold value, this is presumed to denote a switchingintention independently of the progress of the comparison signal 262. Inthe illustrated case, the shifting operation begins a time point t₃. Themonitoring area of the gear lever path extends from a first path s₁ to asecond path s₂. The monitoring time window extends from a time point t₄to a time point t₅. The path change established during the time intervalΔt between the time points t₄ and t₅ within an area s is below amemorized threshold value and, accordingly, a switching intention signalis transmitted to the following operating systems.

[0373] The mode of operation of the switching intention counter will beexplained with reference to FIG. 20. In the embodiment which is shown inFIG. 20, the gear lever signal 260 reaches a peak at the time point t₅.This peak causes a crossing of the gear lever signal 260 with thecomparison signal 262. Thus, the switching intention counter is startedat the time point t₅. In addition, a timer is started simultaneouslywith the switching intention counter. The timer receives a signal whenthe peak of the gear lever signal path 260 decreases which results in arenewed crossing of the gear lever signal 260 with the comparison signal262. The timer is thereby arrested and the then indicated time iscompared with a memorized minimum time interval. In the present case, itis assumed that the time detected by the timer is shorter than thememorized time interval. As a consequence, a control signal istransmitted to the switching intention counter. The switching intentioncounter is thereby arrested and is reset to zero. Thus, a switchingintention has been recognized through the peak at the time point t₅ and,consequently, the switching intention counter has been started but atransmission of the switching intention signal to the followingoperating systems has not taken place since a control signal wasdetected within the control time interval between the starting of theswitching intention counter and the reaching of the maximum count. Incontrast to the above, the switching intention actually existing at thetime point t₆ is recognized and evaluated in the described way. Aswitching intention signal is transmitted to the following operatingsystems shortly after the time point t₆.

[0374]FIG. 21 is a diagrammatic illustration of a clutch operatingsystem 300 for a motor vehicle. The total path which is being consideredis established essentially by the partial system including the engine, asetting member 301 (such as for example an electric setter), aconnecting transmission system 302 and a torque transmission system 303(such as a clutch).

[0375] The setting member 301 can constitute a mechanical or hydraulicor pneumatic setting member. The connecting system which is mountedbetween the setting member 301 and the torque transmission system 302(such as a clutch) can be a linkage in the widest sense or a hydraulicconnecting unit. One embodiment of a hydraulic unit is illustrated inFIG. 21 wherein a master cylinder 304 is connected to a slave cylinder306 by a hydraulic conduit 305.

[0376] A power amplifying device 307 can be mounted in the mastercylinder 304 and/or in the slave cylinder 306. For example, the poweramplifying device 307 can be a spring or a diaphragm spring.

[0377] The torque transmission system 303, such as a clutch, can be afriction clutch and/or a self adjusting clutch or a clutch such as a SACclutch which automatically compensates or adjusts for wear.

[0378] The regulating or control method with path adaption of the clutchoperating system is based on that, as a prerequisite for a successfuladaption, the individual parts of the system are examined for possiblechanges.

[0379] In order to ensure the success of such adaption, it must first beunderstood which problems or which effects can play a role in or canaffect the individual parts of the system and/or can influence anadaption. For this reason, the components mentioned above will bebriefly dealt with again and anticipated sources of defects and problemareas will be pointed out.

[0380] The engine torque is generally determined or calculated from acharacteristic field on the basis of the engine RPM and thesubatmospheric pressure in the suction intake manifold (or, as analternative, the angle of the throttle valve). In the same way, thesolution of the same system or systems can be used to determine theengine torque. Errors in the characteristic field and/or whendetermining the subatmospheric pressure in the suction intake manifoldcan result in deviations from the actual torque. Furthermore, the torquetakeup of the auxiliary aggregates is not known. To this extent, theredevelops a further departure from an accurate determination of theactual engine torque. Still further, special features of the enginecontrol (idling regulator, knocking control, coasting switch off) canlikewise entail faulty conclusions in connection with the determinationof engine torque. An adaption of these special features of the enginecontrol can be taken into consideration in connection with an adaptionstrategy in order to ensure an accurate determination of the enginetorque. The electronic systems which are provided, for example, to turnoff the coasting render it possible to process, for example, signalswhich in relation to terminating a coasting operation transmit a signalto the electronic clutch management in order to ensure as accuratedetermination of engine torque as possible.

[0381] The setting member 301 can constitute an electric setter. In thissystem, a selection of a desired path, for example, of the clutchpressure plate, is converted through a path control or regulation. For aregulation, the knowledge of the actual path is absolutely necessary inorder to be able to regulate in the system without permanent controldeviation. The actual path can be measured and is thus available forfurther calculations. On the basis of a theoretical clutchcharacteristic line, it is possible to calculate from the actual path atheoretical actual torque M_(KIstth) (thus, it is not necessary to usethe desired path and to approximate time behavior of the controlsthrough a model).

[0382] A further possibility of obtaining an additional auxiliary valuefor the adaption is to calculate a theoretical push force by way of thetension and resistance. By means of this push force, it is possible tocalculate a second theoretical torque M_(Kist2). Any changing of thepush force must reflect changes of the clutch torque. If this is not thecase, then corresponding corrections can be carried out. A furtherpossibility resides in the utilization of general forces for thetransmission of torque in that the relevant actual value of the forcescan be compared with the corresponding value of the actual torque inorder to determine whether correspondence of the numerical value isestablished in the engaged and/or disengaged condition of the clutch.

[0383] If a hydraulic system is used as a connection between the settingmember and the clutch, the temperature of the system and the viscosityof the torque transmitting hydraulic fluid medium play a decisive role.Furthermore, the length of the conduits and the cross sections of thepipes can be taken into consideration since, in the event of temperaturechanges and temperature differences, these parameters are subject tovariation and may lead to inaccuracies. For example, the connectingconduit between the slave cylinder and the master cylinder can besubjected to expansion, such as a change of length or a change of thecross section each of which would be indicative of a position other thanthe actual position of the clutch.

[0384] The torque transmission system can be a clutch or a selfadjusting clutch. The so-called influences are to be ascertained as achange of the contact pressure forces or a change of the friction value.The changes which develop in relation to the contact pressure forceswill be described hereinbelow.

[0385] An adaption can also involve a change of the friction value overthe energy input and a change of the friction radius as a change of thefriction energy input.

[0386] An adaption strategy can provide that the clutch torque isadapted only from a certain minimum value, see FIG. 22.

[0387] An adaption of the overall setting system of the clutch actuatorunit (comprising the engine, the setting member, a hydraulic system anda clutch) provides for an identification of the contributions of theindividual partial systems. Each partial system is analyzed and thepossible sources of defects can be detected and the consequences ofthese possible sources of defects can be estimated and eliminated orreduced. It can also be ascertained which sources of defects areimportant and which can be disregarded.

[0388] The adaption can provide for additive shares which are taken intoaccount. The additive shares are intended to encompass those shareswhich are independent of the absolute value or the absolute level of thetorque. For example, the additive share can be taken up e.g., byauxiliary aggregates (consumers ahead of the clutch). However, defectsof the characteristic field of the engine torque can also be compensatedfor through additive shares.

[0389]FIG. 23 illustrates a diagrammatic model or a block circuitdiagram which takes into consideration the additive shares. A block 400contains the engine with the applied engine torque Man. A block 401shows the taking into account of the additive shares of e.g., secondaryaggregates and defects in the characteristic field of the engine. Thecorrection torque M_(Korr) to be introduced thereby is taken intoconsideration at the junction 402. It applies that:

M_(anKorr)=M_(an)−M_(Korr).

[0390] The moment of inertia of the system is considered at the block403. This can mean that, for example, only the moment of inertia of theflywheel or also of the parts of the power train is taken intoconsideration. A dynamically corrected torque is formed at 403 in orderto determine the torque being applied by a clutch 404.

[0391] The torque can be corrected or adapted by a multiplicative share.Sources for the necessity of multiplicative shares are, for example, thechanging friction value, e.g., as a function of the temperature andaging of springs for the linings with their changed springcharacteristics.

[0392] If the assumed and the actual friction values differ from eachother, the error becomes greater the greater the required clutch torque.

[0393] A block 406 in the block circuit diagram of FIG. 23 denotes thevehicle mass.

[0394] An adaption method can be designed in that, in the case of aconsumer adaption, one ensures that the clutch torque (M_(KSoll-Korr))is reduced to such an extent that it leads to slippage of the clutch.This can be explained in that the value of M_(Korr) (correction of theaggregates) is increased according to the equation

M _(KSoll-Korr) =K _(me)*(M _(an) −M _(Korr))+M _(sicher)

[0395] until the development of a slip. During such slip phase, theclutch torque can be increased again according to a predetermined alwaysaccurately defined function (e.g., ramp-like lowering of M_(Korr)) untilthe slip is reduced. Based on such behavior, an evaluation of theconsumer can take place; the evaluation can be carried out each time oronly once or several times per slip cycle.

[0396] In an ideal case when the actual characteristic curve of theclutch corresponds to the assumed characteristic line, the value ofM_(Korr) contains that proportion of the torque which the consumersbranch off or require. On the basis of such estimation or calculation,and assuming the presence of a defect in the engine torque, it ispossible to furnish information concerning the friction value.

[0397] Since there are no negative consumers, negatively adaptedconsumers can be adapted or interpreted as a friction value which is toolow. Furthermore, the torque takeup of the individual consumers isrestricted, and the corresponding absolute level need not be known atall. Thus, exceeding a threshold value can be interpreted as a frictionvalue which is excessive.

[0398] Based on an appropriate selection, fixing of an upper barrier orthreshold value renders it possible to avoid the selection of a valuewhich is excessive so that the detection of a change of the frictionvalue would be too late. It can likewise be avoided that, when thethreshold value is too low, the secondary consumers would be interpretedas a change of the friction value.

[0399] It can be advantageous if the adaption is carried out only in thecourse of a pulling operation; in such event, the adaption should becarried out above a minimum torque.

[0400] Such simple adaption method (see also FIG. 14) entails that asplitting of the adaption model into an additive portion (consumers,etc.) and a multiplicative portion takes place only by fixing ordetermining the limits. Within the limits, the portion is assumed to beadditive, and outside of the limits the portion is assumed to bemultiplicative defects of other causes, such as for example of theengine torque.

[0401] In this manner, an error or a breakdown of the engine torque isadded to the consumers or to the characteristic curve of the clutch.

[0402]FIG. 24 provides an example of an embodiment, namely an estimateor appraisal of the additive and multiplicative portions in the slipphases with different load conditions.

[0403] The curve 450 denotes the timely progress of the corrected clutchtorque. The curve 451 indicates the timely progress of the engine RPMn_(mot), and the curve 452 the timely progress of the gearbox input RPMn_(Getr).

[0404] At the onset of the observation time point shown in this example,the engine RPM 451 is approximately equal to the gearbox RPM 452. Thecorrected clutch torque shows a slightly decreasing time behavior.

[0405] A slip phase takes place during the time interval 453 and theengine RPM 451 is slightly above the value of the gearbox RPM. Theclutch torque 450 rises after the detection of the slip phase. At thetime instant 456, the engine RPM 451 reaches a relative maximum and theincrease of the clutch torque permits the engine RPM to drop again.

[0406] A so-called tip-in takes place at the beginning of the timeperiod 454, i.e., an increase of the engine RPM is introduced for ashort interval of time. No adaption takes place during this phase andthe gearbox RPM follows the engine RPM 451 with a time delay.

[0407] The time period 455 involves a slip phase, the same as the timeperiod 453.

[0408] Since the consumer adaption is or can always be close to the sliplimit, there exists the additional possibility of evaluating those slipphases at which the overall contact pressure changes or has changed,i.e., the desired torques at the clutch or at the torque transmissionsystem lie at different levels, for example, by showing different enginetorques and/or load conditions. A prerequisite for this is that theactual consumer has not changed, i.e., too long a time span between theslip phases is not a very favorable indication.

[0409] If the consumer value, does not change at different loadconditions, such as in the slip phases 453 and 455, it can be taken forgranted that the assumed and/or determined and/or calculated frictionvalue corresponds to the actual friction value of the clutch.

[0410] In such a case, the friction value can be corrected or acorrection can be carried out.

[0411] In this embodiment, it is advantageous to carry out a divisioninto an additive to and a multiplicative portion.

[0412] In the event of a consumer change during the interval ofadaption, a separation of a friction value change and a consumer changecannot be correctly carried out; however, this can be compensated for toa large extent through an increased frequency of the adaption procedure.

[0413] Furthermore, it is possible to carry out adaption during theconstant phase after load changes, and such adaption can be combinedwith other adaption strategies as a result of potentially long intervalsof time.

[0414] It is also possible to carry out an adaption of themultiplicative portion in dynamic areas or cases, such as e.g. a tip-inand/or during starting. In the event of a slip, it applies that${M_{an} - M_{korr} - {\frac{\mu_{ist}}{\mu_{theo}}*M_{{KSoll}_{korr}}}} = {J*{d_{dt}^{\omega}.}}$

[0415] By means of this equation, it is possible to detect the unknownvalues, μist and μtheo being the actual and theoretical friction values.

[0416] This adoption method will be explained in greater, detail withreference to FIG. 25 which shows the timely behavior of the appliedtorque 500, of the actual clutch torque 502, engine RPM 501, J*dω/dt503, the gearbox RPM 504 and the corrected desired clutch torque 505.

[0417] In the phase 506 in which the applied engine torque 500 isconstant, a change of J*dω/dt 503 must be correlated with a change ofthe corrected desired clutch torque when the selected clutch torque 505does not change. However, such condition is fulfilled in most situationssince, as a rule, the consumers hardly change on short notice. If thesealterations are not correlated, i.e., if a change of the correcteddesired clutch torque 505 does not entail a change of J*dω/dt (503), thefriction value must be corrected accordingly. If the change of thecorrected desired clutch torque 505 exceeds that of 503, the theoreticalfriction value must be lowered because the actual friction value is lessthan the assumed value. If the reverse happens, it is necessary toproceed accordingly.

[0418] This method renders it possible to directly calculate ordetermine the friction value. It is therefore possible to calculate thelevel of the value of the secondary consumers at a point of time whenthe engine RPM gradient is zero, such as e.g. at the positions 507,because the engine torque is known. At such time, it applies that:$M_{korr} = {M_{an} - {\frac{\mu_{ist}}{\mu_{theo}}*M_{{Ksoll}_{korr}}}}$

[0419] Since the setting member lies between the calculated desiredtorque ^(M)Ksollkorr 505 and the actual torque of the clutch 502, andsince as a rule the setting behavior is not to be disregarded, it ispossible to carry out a modelling of the setting member in order tofurther enhance the quality of adaption in dynamic cases. If the settingdevice of an electronic clutch management system is operated by anelectric motor, it is possible to calculate, based on a pathmeasurement, for example, in the master cylinder, a theoretical actualtorque 502 from the measured actual path and a characteristic line. Thiscan be used in lieu of the desired torque and shall be designated asMK_(ist) 502 . In this manner, one circumvents the dynamic proportionwhich arises through the path regulation. The adaption method isparticularly advantageous under all driving conditions when a slipoccurs. It is likewise advantageous that a division into amultiplicative and an additive portion can take place.

[0420] A further possibility for adaption offers the identification ofthe multiplicative portion through the evaluation of starting speeds.This simple possibility of identifying the additive and multiplicativeportions consists in the evaluation of a starting procedure. At thepoint of time when the engine is idling at an idling speed, the driverhas not caused the admission of any fuel and the torques being appliedby the engine are used to satisfy the needs of the engine and tocompensate for the auxiliary aggregates. Therefore, the value of theengine torque which is assumed to exist in such situation can be assumedas the reference or starting point for the value of the correctedtorque. During starting, when the driver steps on the gas pedal, thereached engine RPM is evaluated at a certain point of time. The engineRPM is related to the applied clutch torque which is the actual enginetorque minus the engine torque shortly prior to the admission of fuel.It is possible to resort to a table in order to compare whether theengine RPM pertaining to the applied engine torque corresponds to theactual engine RPM. In the case of larger deviations, a change of thefriction value exists and the friction value stored in the controlcomputer can then be corrected accordingly.

[0421]FIG. 26 shows the applied engine torque 510 and the engine RPM 511as well as the gearbox input RPM 512 as a function of time. The vehicleis idling prior to a time 517, and the power or torque takeoff of theauxiliary aggregates is evaluated based on the values in the range 513.During the interval following the time point 518 which is fixed after anacceleration phase, a desired engine RPM can be determined from thevalue of the applied engine torque and this desired RPM can be comparedwith the actual value 511 of the engine RPM and thus an estimation canbe made of the friction value. This procedure allows a division into amultiplicative and an additive portion. No effects can be detected inthe case of a dynamic change of the setting member. The adaptionaccording to this method is characterized in that it is only possiblewhen starting and a defect of the engine torque signal can influence theadaption.

[0422] A further possible method of adaption can consist in that theidentification of the entire characteristic curve is carried out usingpoint-like supporting spots. This possibility, for systems with adetectable setting value, such as the position of the disengaging systemor the disengagement path, can advantageously be applied for thecalculation if at the beginning of a dynamic adaption the adaptive part,the consumer torques and/or aggregate losses are known at leastapproximately. A calculation of the offset signal in the case of unknownconsumer torques and aggregate losses could also be carried out byundertaking the determination through numerical processes.

[0423] In order to identify the characteristic curve, one could compare,at certain path points or supporting points of the characteristic curve,the corresponding calculated theoretical clutch torque 520 (FIG. 27)with that based on the characteristic clutch curve and the actual path521. In the event of a departure, the supporting spots would then becorrected incrementally, and it then applies that:

^(M) kupplungtheo= ^(M) an− ^(M) korr−J*dω/dt.

[0424]FIG. 27 shows a change of the actual distance covered by thesetting member on the basis of the actual value 522 in a time window 523and the gearbox RPM 525. By using the supporting spots 526, it ispossible to determine from the actual path and from the knowledge of thecharacteristic curve of the torque transmission system the correspondingcalculated clutch torque 520 which can be compared with the actualclutch torque. FIG. 27 shows these values as a function of time, thesupporting spots 526 being adapted to be defined by using theinformation regarding the location of the path of the setting member,and the spreading out of individual supporting spots takes placeaccording to the speed of movement of the setting member.

[0425]FIG. 28 shows a characteristic clutch curve 530 with supportingspots 531 at which the clutch torque is determined and calculated.Furthermore, there is shown the adaption range 532 which need not befixed for the entire length of the characteristic clutch curve. It canbe advantageous if the torque area is adapted above a threshold value533 and an adaption below the threshold value 533 takes place in orderto set a minimum value as proposed, for example, in FIGS. 15a to 15 e.Such adaption can be independent of the recorded basic path of thecharacteristic curve. Errors of the theoretical characteristic curve arecompensated for.

[0426] Consequently, the adaption of supporting spots also affects theoperating areas which do not lie on the supporting spots; however, anextrapolation is necessary in such cases since the adapted operatingpoints are not or need not necessarily be touched.

[0427]FIG. 29a shows diagrammatically a power train of a vehicle with adriving unit 600 and a torque transmission system 601 connected in thepower flow at the output side of the driving unit. An automatic gearbox610 is installed at the output side of the torque transmission system,the automatic gearbox being illustrated diagrammatically as a conepulley belt contact gearbox without being restricted thereto. Thegearbox can also be an automatic infinitely adjustable gearbox, such asfor example a friction wheel gearbox or a friction ring gearbox.

[0428] The cone pulley belt contact consists essentially of a variatorwhich is assembled of two pairs of cone pulley sets 602 a, 602 b, 603 a,603 b, and an endless torque transmitting device such as an endless beltor chain 604.

[0429] At least one fixed transmission stage 605 is connected at theoutput side of the variator of the cone pulley belt gearbox and actsupon a differential 606.

[0430]FIG. 29b shows the same structural arrangement except for theposition of the torque transmission system 611 which is installed in thepower flow at the output side of the gearbox 610, such as a variator.

[0431] The contact pressure of the device 604 is selected in such a waythat it does not permit a slip of this device relative to the sets ofcone pulleys. A control system regulates the contact pressure of theendless device 604 between the pairs of cone pulleys in order to preventa slip since slipping can lead locally to damage and even to destructionof the endless flexible device.

[0432] In the event of a change of the applied engine torque, anadaptive regulation can select the transmissible torque in advance or asa follow-up and a change in the operating point can result in slippingof the contact or endless flexible device, such as a chain.

[0433] The pressure of the endless device must take place with an excesscontact pressure in order to avoid, in the event of for exampletorsional vibrations in the power train, any slipping as a result of atemporarily increased adjoining torque.

[0434] The application of contact pressure with the lowest possibleexcess contact pressure is desirable since the excess contact pressureleads to friction losses and thus to a reduction of the efficiency andan increased fuel consumption. A reduction of the excess contactpressure can lead to the danger of slippage of the device 604.

[0435] The aforedescribed fluctuations of the torque which is beingapplied and which is to be transmitted by the variator can be calculatedand taken into account by means of a control method since a dependencyupon the operating point can be adapted.

[0436] Furthermore, unforeseen torque surges can take place at theoutput side, such as for example if the vehicle passes with turningtires from a smooth road surface to a non-skid road surface. Under suchcircumstances, a torque surge which cannot be calculated in advancedevelops at the output side. Neither the timely progress nor theamplitude of such surges can be calculated in advance.

[0437] In order to protect the variator from such torque surges, and asshown in FIGS. 29a and 29 b, a torque transmission system 601, 611 ismounted in the power train and is controlled in such a way that thetorque which can be transmitted by the torque transmission system isalways less than the torque which can be transmitted by the variator.

[0438] The application of transmissible torque of the torquetransmission system 601, 611 guarantees at each operating point that thetorque which can be transmitted by the variator is greater than thetorque which can be transmitted by the torque transmission system. Thus,the torque transmission system constitutes a torque-guided overloadclutch which can be adaptievely controlled at each operating point. Dueto the adaptive control of the torque transmission system, it ispossible to reduce the contact pressure of the contact means so that thesafety reserves for protecting against slippage of the contact means canbe reduced. Thus, the efficiency of the gearbox can be increased withoutendangering the safety of the variator.

[0439] The torque transmission system can be used as a discrete safetyclutch and/or as a turning set clutch and/or as a lockup clutch in atorque converter or additionally as a clutch for adjusting the variator.

[0440] The mounting of the torque transmission system at the output sideis particularly advantageous because load surges are detected earlier atthe output side than in an arrangement at the input side since, in thecase of introduction of a torque, the rotary masses of the variator arestill effective.

[0441] An arrangement at the output side exhibits the additionaladvantage that, when the vehicle is at a standstill but the engine isrunning, the variator rotates and rapid adjustment or an adjustment fromstandstill can be carried out more rapidly.

[0442] If the torque transmission system is installed at the outputside, it is necessary when determining and/or when calculating theapplied engine torque to take into account the transmission ratio of thevariator and the losses.

[0443] The invention is not limited to the illustrated and describedembodiments but also encompasses especially those modifications whichcan be arrived at through a combination of features and elementsdescribed in connection with the present invention. Furthermore,individual features and methods described in connection with thedrawings can be considered to constitute independent inventions.

[0444] The applicants reserve the right to claim, as being important forthe invention, additional features which at the present time aredisclosed only in the specification, especially in connection with thedrawings. Thus, the claims filed with this application are merelyproposed formulations without prejudice to achieving broader patentprotection.

We claim:
 1. A torque transmission system for transmitting torque froman input side to an output side of a drive train of a motor vehiclehaving an engine and a cone pulley gearbox, the torque transmissionsystem comprising: at least one component adapted to transmit torque,wherein the torque transmission system is controlled in such a way thatthe torque which can be transmitted by the torque transmission system isalways less than the torque which can be transmitted by the cone pulleygearbox.
 2. The torque transmission system according to claim 1, whereinthe cone pulley gearbox comprises: a variator assembled of two pairs ofcone pulley sets; an endless torque transmitting device; and a controlsystem, which regulates the contact pressure of the endless torquetransmitting device between the pairs of cone pulley sets.
 3. The torquetransmission system according to claim 1, wherein the at least onecomponent comprises at least one clutch a torque-flow path before orafter the cone pulley gearbox.
 4. The torque transmission systemaccording to claim 1, wherein the torque transmission is controlled toprevent rotary oscillations originating from the engine and causing anexcessive contact pressure to be exerted on the endless drive.
 5. Thetorque transmission system according to claim 2, wherein the torquetransmission system is controlled to protect the variator from torquesurges at the output side.
 6. The torque transmission system accordingto claim 1, wherein the at least one component comprises a discretesafety clutch.
 7. The torque transmission system according to claim 1,wherein the at least one component comprises a lockup clutch of a torqueconverter.
 8. The torque transmission system according to claim 1,wherein the at least one component comprises a clutch of a turning set.9. The torque transmission system according to claim 2, wherein saidtorque transmission system has an additional clutch for adjusting thevariator.
 10. A torque transmission system for transmitting torque froman input side to an output side of a drive train of a motor vehiclehaving an engine and a cone pulley gearbox, the torque transmissionsystem comprising: at least one clutch for transmitting torque, whereinthe at least one clutch is controlled in such a way that the torquewhich can be transmitted by the torque transmission system is alwaysless than the torque which can be transmitted by the cone pulleygearbox.
 11. The torque transmission system according to claim 10,wherein the cone pulley gearbox comprises: a variator assembled of twopairs of cone pulley sets; an endless torque transmitting device; and acontrol system, which regulates the contact pressure of the endlesstorque transmitting device between the pairs of cone pulley sets. 12.The torque transmission system according to claim 10, wherein the atleast one clutch is selected from the group consisting of a discretesafety clutch; a lockup clutch of a torque converter, and a clutch of aturning set.
 13. The torque transmission system according to claim 10,wherein said torque transmission system includes an additional clutchfor adjusting the variator.